Orchestration of information and warning sounds in a car.

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M A S T E R ' S T H E S I S

Orchestration of Information and Warning Sounds in a Car

Josefin Grönlund

Luleå University of Technology MSc Programmes in Engineering Arena, Media, Music and Technology

Department of Human Work Sciences Division of Sound & Vibrations

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warning sounds in a car

Josefin Grönlund

May 14, 2008

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This report presents how new information and warning sounds in a car were created and tested, to see what makes a chime understandable, premium and suitable for a Volvo. Premium is in this thesis defined as high quality and luxury.

The amount of information to the driver is increasing and thus also the necessity of methods to make it possible for the driver to understand and respond to the message in a correct way without disturbing the driving.

The sounds should keep high quality and acceptance.

Chimes of various categories were created in a music computer program.

Both a pilot study containing a listening test on tone and a chime listening test were carried out to analyze the sounds.

The tests showed that if a chime is repeated continuously, it is understood as a reminder – most often as seat belt reminder. But the seat belt reminder should be a dedicated sound to avoid confusions. A general information chime is most easily recognized and suitable if the sound is a simple melody of a few notes or consists of beeps, like typical information jingles heard for instance at a train station or from a computer. The warnings of high urgency should be alarming, fast, clear and loud but not frightening. A sound is judged as premium if it is soft, clean and round.

The tone of a flute is not premium in this context. Another instrument, namely trumpet, which constitutes two warning sounds, is not appreciated either. The participants expressed that a Volvo sound should be like a premium sound and should also sound secure and be understandable.

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Thanks to my supervisors, Martin Fagerström and Thomas Lindgren, and other co-workers at Volvo Car Corporation. It has been a privilege to work with you.

Thanks to my supervisors, professor Anders Ågren and Arne Nykänen at LTU, who has guided me through this process.

Thanks to the Sonic Studio group at Interactive Institute in Piteå, for let- ting me use your studio and for instructing me how to use it.

Thanks to Malin Albing at the Department of Mathematics at LTU, for help with the statistics.

Thanks to Caroline Vilsson for help with the english language.

Thanks to my family and friends for support and crazy ideas.

David, Thank you.

And finally a huge thank you for everything to The One.

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1 Introduction

The development of technologies makes it possible to detect different kinds of occurrences and threats in the traffic surrounding the car. In- formation about this and services like telephone and email are making their way into the car. Together with the already existing information about speed and fuel level, there is a lot of information for the driver to adopt. Since the visual modality already is heavily strained, many new chimes and tinkles want to deliver information without competing with the concentration on the traffic.

This report assesses suggestions of several sounds that could be used as information bearer in an in-vehicle situation, in this work referred to as chimes. The design of the chimes is supported by conclusions from ar- ticles that discuss psychoacoustics, human perception, auditory warnings and sound strategies. It is of great importance that the chimes are accepted and understood, so the sound is not switched off and no mea- sures taken on the error. How is that done? What makes a sound deliver a message and inform the listener about an action that has to take place? What makes it sound luxurious and high quality, in Volvo-words, Premium? What is a volvoish sound? And what could it sound like?

By order of the supervisors at Volvo Car Corporation, only chimes connected to the purpose from four warning groups were made and tested.

The warning groups were informational (I), reminder (R), warning low (WL) and warning high (WH). No reaction, response or response time to the chimes were tested, only the participants’ opinions.

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2 Theory

This section gives an insight in parts that can affect the understanding of, attention to, taste of, opinion of, reaction to and response to sounds.

There are two main groups of sound, noise aside: speech and non-speech.

Speech is easy to understand – a big amount of information or complex information can easily be delivered. On the other hand speech is dependent on language, something that non-speech is not to the same extent.

Non-speech can make you understand and respond quickly. If there is a lot of other speech heard or other noise, a non-speech sound can be eas- ier to hear. One division of non-speech is auditory icons and earcons.

These match different situations depending on response time, annoy- ance and urgency. (Fagerlönn 2007b)

2.1 Earcon and auditory icon

An earcon, is like a jingle. It can be anything between a single simple beep to more of a complex melody. The meaning of the earcon can not be figured out by its content but has to be learned.

Unlike earcons, auditory icons could be understood even the first time they are heard. An internal division of the auditory icons is nomic, symbolic and metaphoric mapping (Edworthy & Stanton 1995). Nomic mapping is the actual sound of the event. An example from the everyday life is the sound of opening a can with a can opener. Metaphoric mapping can be the sound of something totally different but evokes some kind of association to the event. The opening of a squeaky door could be a metaphoric mapping of opening a can. Symbolic mapping is a sound of something related to the event or a created sound that is similar to the sound of the event. A symbolic mapping of opening a can could be a tone sweeping from low to high frequency.

Recognition of a direct relation sound requires little training. Symboli- cal and metaphorical associations affect learnability equally, at least for relatively easy tasks (Keller & Stevens 2004).

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sociation to the auditory icon. It is not always possible to find a direct association. Icons with a direct association is better than an indirect relation, if there is no specific objection that would make it inappropriate (Stephan et al. 2006).

In an experiment performed by Lemmens et al. (2001), it was found that earcons slow down the response time and auditory icons have the oppo- site effect. It is very important that the sound and the visual event make a unanimous unit to avoid even slower responses than with neutral con- ditions.

2.2 Perceived urgency

According to Edworthy et al. (1991) the parameters that unturbidly effect the perceived urgency are: fundamental frequency, harmonic series am- plitude envelope shape, delayed harmonics, speed, rhythm, pitch range and melodic structure.

A later study by Haas & Casali (1995) has confirmed and explored some of the parameters. It showed that regular rhythm of pulses is more urgent than irregular pulse rhythms and inter-pulse intervals should be kept as short as possible. The mean response times for high pulse rate turned out shorter than for low pulse rate. In their example with pilots the response time was actually 60 ms faster with a high pulse rate. Such a short time- range as 60 ms can be a dividing line between a crash and no crash in an emergency in air traffic. Even in a traffic situation on the ground parts of a second can make a huge difference.

Sequential pure tone signals lead to longer response times than simulta- neous and frequency-modulated tones (Haas & Casali 1995). Hellier et al.

(1993) had also earlier found that speed and frequency was alerting parameters, but that speed had a deeper impact. A change in pulse rate and repetition rate will faster obtain a difference in perceived urgency than a change of fundamental frequency.

The sound of emergency vehicles directly gives a feeling of urgency. And sequences with two alternating tones were in a study caught as more urgent than others. The most effective alarms are those that eventuate in an immediate association and from that a direct response like a hard brake

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(Guillaume et al. 2003).

A spontaneous response to the relation between annoyance and urgency is that the more annoying a sound is the more urgent it is perceived. But according to studies by Marshall et al. (2001) parameters that make a warning sound more urgent is not necessarily more annoying. To get a high urgency warning with fairly low annoyance, the sound should have high density, a slow speed and contain frequency series.

2.3 Driver’s workload

Driving is a complex situation with a lot of impressions to deal with and make decisions from. Inside the car there are lamps and icons that are lit to keep the driver posted about the state of the car. More advanced visual displays are making their way into the car and the workload, that is already heavy saddled with the traffic situation, gets yet another source of information to deal with. With these displays follow sounds of different kind. Trials with both visual dash-mounted display and conventional auditory warning or auditory icon evoked faster response times than with only the visual display. The same result was found with solely auditory icons. But the combination of visual dash-mounted display and auditory icon resulted in fewer collisions in the test. In the situation of a front- to-rear collision the participants preferred auditory and dash-mounted visual display. For side collision warning the most preferred was mirrors, dash-mounted visual display and auditory display all together (Belz et al.

1999).

The brain has a lot of data to process, and information in various cos- tumes seems to be the best solution. The auditory and tactile information facilitate the sight. It is suggested a multimodality display to achieve this. This is also what the participants in a study by Liu (2001) preferred to use. But in a combination of complicated driving and a lot of instructions produced, a memory interference problem appears and even the auditory display is hard to observe. What kind of presentation that suits the best is dependent on the situation. It is also important to make the information or instructions simple in order to decrease the workload.

Wiese & Lee (2004) saw a tendency that annoyance may affect the work-

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noyance ought to be more considered than perceived urgency. This is supported by Marshall et al. (2007). They found that appropriateness is more related to perceived annoyance than to perceived urgency. Some parameters affect perceived urgency more than perceived annoyance.

The context affects both perceived urgency and perceived annoyance.

The parameters that improve perceived urgency without large changes in perceived annoyance were: pulse duration, interpulse interval, alert offset, alert duty cycle and sound type.

2.4 Music

Music has a way of influencing a persons mood. This is prominent especially in computer games and films. Music is there to create an at- mosphere and convey warnings about danger, excitement, harmony and so on. Short sequences of music in various constellations with low and medium levels of urgency can be understood even in a traffic situation as warnings. In an experiment the warnings were not experienced as annoying but may be unappropriate the more urgent the situation is (Fager- lönn 2007a).

2.5 The way of listening

Depending on the situation, humans listen to sounds in different ways.

When listening to music, we can hear a specific component, a specific in- strument. This is called musical listening. But when we hear sounds that occur because of a subject’s shape and material and an occuring event, we mostly listen to the event or the source of the sound, not its acoustical components (if it is not intentional). In other words we do not listen to which frequencies are involved, the timbre, the rhythm, but that a fast snowmobile is approaching on a snowy field. This is called everyday lis- tening (Gaver 1993).

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2.6 Volvo sound strategy

The Volvo sound strategy suggests six categories of information sounds:

Warning high, warning low, reminder, informational, feedback and infotainment informational. They represent different situations in the driving process. Warning high is extremely urgent, the response time has to be less than one second, the situation has severe imminent danger.

Warning low signals possible danger and has a response time limit to ten seconds. The informational chime invites the driver to take some action.

The reminder also invites the driver to take some action but because of some by the driver forgotten action. Feedback informs of action initi- ated by driver or passenger. The infotainment informational gives signals about the infotainment system (Davidsson & Fagerström 2007).

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3 Method

3.1 Analysis and presentation of problem

The existing chimes in Volvo cars are few and relate to several different actions. This is confusing to the driver. Since the chimes usually do not sound especially often, it can be hard to know what they mean. Learning- time does not exist, except for the seat belt reminder, which might occur every time the driver is seated.

A common chime, like the seat belt reminder, should be easily accepted and discreet. There are in the present no particulary volvoish sound except the seat belt reminder, which perhaps is too simple to be premium.

3.2 Pilot study on tone

To get a clue about the relation between tone and premium, a simple listening test was made (Appendix B). Four different tones, collected from the music computer program Steinberg Nuendo Version 3.2.1, were tested.

Vibraphone, Synthesizer sound like a damped vibraphone, trumpet and a flute. These four sounds are more or less well-known instruments with different characters and tones. A note 525 Hz (C5) was played two times for each tone. The participants were asked to grade them and by pairwise comparison decide which tone was most premium.

The eleven participants, six women and five men in the ages between 17 and 61, where all in the author’s circle of acquaintances. The majority of them were amateur musicians and some of them had used computer music programs like Cubase.

It showed that the airy tone of a flute was experienced as not especially premium, neither the trumpet. The synthesizer sound with its soft and sonorous tone was elected as the most premium tone. There were also comments about the difference in the quality of the tones as the signal to noise ratio and that some sounded as flat and simple midi files.

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3.3 Creating the chimes

The chimes were created in the same program as the tones, Steinberg Nuendo Version 3.2.1. With respect to the tone listening test, a literature study, the Volvo sound strategy and the existing chimes, the new chimes were developed. The suggestions belonged to four categories represent- ing four urgency grades. The following situations should have chime suggestions. Forward collision warning (FCW), parking brake (PB) ac- tive while driving, seat belt reminder (SB) and information (Info) of any kind. The situations belong to the four categories respectively, warning high (WH), warning low (WL), reminder (R) and informational (I) (table 1).

Table 1: Excerpt from the Volvo sound strategy 1.4

Name Type Sound character Pitch Repetition Duration FCW WH Dedicated chime. The sound

character shall convey a high urgency/criticallity message. Ac- ceptance not that critical. Ex- ample: CAMP sound

high short interval

3 cycles

PB WL General chime. The sound character shall convey a high urgency/criticallity message. Ac- ceptance of the sound has to be considered.

medium cont. in-

creasing

SB R Dedicated chime. Premium, acceptance of the sound is of high importance. Classic belt reminder.

medium cont. in-

creasing

Info I Premium, acceptance of the sound is of high importance

medium short interval

1 cycle

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3.3.1 The author’s initial scattered thoughts about the new chimes

This section contains the author’s first ideas from which the chimes later were developed. Some of the ideas were similar to the Volvo strategy. The items in this section were not handled as demands but as guidelines.

• All the chimes should be suitable in a Volvo, informative or in other words give a hint of the meaning, intention or the desired action.

Every chime should also be judged as Premium. This is less important for the more urgent chimes, especially the FCW.

Forward Collision Warning (FCW) - Warning High

• To signal the urgency and elicit a fast correct response, as a hard deceleration.

• Signal horn - short pulse and interval (Hellier et al. 1993, Haas &

Casali 1995, Guillaume et al. 2003, Keller & Stevens 2004, Stephan et al. 2006, Marshall et al. 2007).

• Loud! 15-30 dB over the noise (Haas & Casali 1995, Baldwin & Struckman- Johnson 2002).

• Strong, lots of bass, or sharp and more of the high frequencies.

• Placement - from the threatening direction.

• Low acceptance. It is there to alert danger.

Parking brake - Warning Low

• Creating a feeling of that something is wrong and an action should take place in a fairly short time period.

• Metal scrape, sound of a parking brake being pulled, voice.

• Placement - by the parking brake, driver’s seat.

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• Mean acceptance. The sound should not come often.

Safety belt - Reminder

• Should request the driver or passenger in a nice and not annoying way, to fasten the seat belt.

• Intensifying and more sharp as time goes by.

• A bit dissonant. Consonant when seat belt fastened.

• Two or three notes.

• Pretty slow notes.

• Placement - by the driver and the seat in question.

• Mean acceptance since the sound comes often.

Information - Informational

• Make the driver aware of that information is available on the display.

• Typical information bell, voice.

• Placement - in front of the driver.

• Good acceptance. The sound should inform in a nice and friendly way.

3.3.2 The author’s intention with the characters in the final chime suggestions

In consultation with co-workers and supervisors at Volvo, three sounds in each category were chosen, except for the information chime where four sounds were chosen, since there was no existing chime of that kind.

For a more detailed description of the sounds see table 2 and 3.

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The info chimes were meant to sound similar to typical information sound for instance from the computer or at the train station. They were, above all, short.

The seat belt chimes were all continuous and slow. The sound of SB1 was put together to be friendly and bright. SB2 and SB3 were a bit dissonant to signal, like ambience music in a film, that something is wrong and has to change.

There were trials of making an auditory icon for the parking brake chime.

Sounds of different metal scrape and the mechanical sound of the parking brake handle being pulled were recorded and adjusted, but they were in the author’s ears, hard to understand and connect to their purpose.

Instead, a clearly dissonant tone was used in PB1 and PB2. PB3 had another variant of musical approach. It was made of three slightly dissonant falling notes, and was meant to sound nice but give a hint that all is not well. The PB chimes were as the Info chimes, short. They were intended to be repeated if no action had taken place.

As mentioned in section 2.2 auditory icons increase the response time and would therefore be appropriate in an emergency. The only chimes that were auditory icons were the FCW chimes. The FCW1’s sound was a modified recording of a horn in a Volvo S80. It staged the scenario of a threat in front of the car. A car horn is to some extent a trumpet sound.

And this was taken into account when FCW2 and FCW3 were created.

They were both based on a trumpet tone. The only difference was the speed of the pulses and notes. All the three FCWs were rapid and continuous pulses.

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Table2:Descriptionofthecreatedandexistingchimes.(Musicalapproach) NameTypeContin- uousNotecharacterStyleSpeedTone(Nameofthe synthinbrackets)Sustain Info1I-TwonotesC5Airy,distinctShort,fastWoodwindsflute (Hypersonic2)- Info2I-FirstC6andthenthe octaveC7(dominating)MuchtoneShortnotesCelesta(Hyper- sonic2)Some Info3I-TwonotesC5Computer soundShort,distinctElectricPianos FlexibleSuitcase (Hypersonic2)

- Info4I-LegatoG4,A4andC5Verysoft,dullShortFMMelodyJH(A1 AnalogSynthUnit)Some SB1RYesFirstD5andthenA5SoftSlowElectricPianos FlecibleSuitcase (Hypersonic2)

Long SB2RYesNotesG4andD5Verysoft,dullSlowFMMelodyJH(A1 AnalogSynthUnit)Long SB3RYesNotesG4andD5like slowheartbeatVerysoftSlowVibraphone2soft XXL(Hypersonic2)Long SB4RYesOnenoteF#5Soft,slightly piercingSlowExistingVolvo chimeSome PB1WL-NoteG4andG#4intwo thrustsPrettysoft,dis- sonantMiddletempoMalletsVibra- phone2softXXL (Hypersonic2)

Some PB2WL-G5andG#5three thrustsPrettysoft,dissonant,distinctShortElectricPianos FlexibleSuitcase (HYpersonic2)

- PB3WL-LegatoC5,Bb4andG4, three"falling"notesSoft,sadhar- monyMiddletempoFMMelodyJH(A1 AnalogSynthUnit)Some PB4WLYesOnenoteB5Soft,slightly piercingSlowExistingVolvo chimeLong FCW1WHYesTwonotesA4andC5 fastlyalternating,short attack

Dissonant,dis- tinctShort,fastnotesHorninVolvoS80- FCW2WHYesFourshortthrustsofA4 inthreeroundsShortattack, distinctShort,fastnotesSolobrasstrom- bone(Hyper- sonic2)

- FCW3WHYesFourshortthrustsofA4 inthreeroundsShortat- tack,distinct, bouncy

Short,veryfast notesSolobrasstrom- bone(Hyper- sonic2) - FCW4WHYesNoteA4Notsosharp, fastattackShort,fastnotesExistingVolvo chime-

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Table3:Acousticalquantitiesofthecreatedandexistingchimes.Theapproximatedvaluesareinterpreted fromthegraphsinAppendixC. NameTypeFrequency[Hz]Sharpness [S/acum]Tonality [Ton/tu.]Roughness [R/asper]Duration [s] Info1I525,1050(dominating)4.50.73.00.3 Info2I1050,2010(dominating)6.00.89.51.1 Info3I10502.50.88.50.6 Info4I386,440,5152.01.18.50.9 SB1R592,8723.51.14.01.1 SB2R387,5921.01.11.20.7 SB3R387,5921.71.12.61.8 SB4R753,withharmonics3.31.00.71.2 PB1WL387,4205.00.912.01.3 PB2WL786,8303.30.714.00.4 PB3WL516,462,3872.21.18.50.9 PB4WL980withharmonics3.31.00.41.2 FCW1WH430,510withharmonics8.70.59.00.25 FCW2WH440withmanyharmonics11.50.710.50.4 FCW3WH440withmanyharmonics10.50.412.50.3 FCW4WH440withharmonics2.61.11.30.5

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3.4 The existing chimes and background noise

The existing chimes were recorded in a Volvo S80 with Head Acoustics NoiseBook.

To get a more realistic feeling in the test, car background noise was added to the chimes. The background noise was recorded with Head Acoustics NoiseBook in a Volvo XC70 with winter tyres without studs, driving on a even, dry asphalt road. One sequence was recorded when the speed was 90km/h and the other one was start of engine and departure. For acous- tic quantities such as loudness see Appendix C. The continuous background noise was added to the Info and FCW chimes. The start noise was added to the PB and SB chimes. The proportion between the levels of signal and noise was adjusted by listening and comparing with a real driving situation.

3.5 Testing the chimes

The listening test was performed in a sound car of model Volvo S80 - 01 to give a more realistic feeling. The sound car had a computer with Head Analyser Artemis version 6.00.200 installed and two headphones, Sennheiser HD600. The participants were placed in the driver’s seat and the test leader in the front passenger seat.

The test leader was present during the whole procedure to note spoken thoughts, explain obscurities and to manoeuvre the chimes.

The chimes were presented in four different orders, to avoid different kinds of side effects. Hence each order were heard by three or four participants.

The test participants wrote down their opinions in a questionnaire containing both grading and open questions (see Appendix D). The open questions dealt with the comprehension of the chimes and suggestions of what qualities a chime should have corresponding to its information and character. The grade scale was from one to ten, with explanatory words to each step. This is the scale that is most often used in tests at Human Machine Interaction department at Volvo Car Corporation. The

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Volvo, suitability to the sound category, frightening and attention grab- bing. The two latter were only considered for the FCW chimes. One task was also to match the chimes with four warning degrees.

3.5.1 Selection of the participants

The participants were chosen from a test pool within Volvo. The only de- mand on the participant was that he or she was in possession of a driver’s licence. The desire was to have a uniform age structure and gender dis- tribution. Since only 14 persons gave their positive response to the invi- tation all of them were selected, six women and eight men. The age span was between 28 and 57 with a mean of 44 years.

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4 Results

Since the questions of open character results in answers where the words are not exactly alike, the answers have been categorized into larger groups by the author. The author listened to the chimes several times and at the same time read the answers to understand how to interpret them. The words that were most often used are those presented in this report. That also goes for words that described the sound in different ways but in the same spirit.

4.1 Question 1 - What do you think the sound intends to warn or inform about?

The parking brake sounds and information sounds were mostly understood as some kind of information and sometimes as a mild warning.

Further some thought that PB2 and PB4 sounded like a park assist. One especially remarkable thing was that PB4 was understood of twelve participants to be seat belt reminder.

The seat belt reminder chimes were mostly interpreted as seat belt reminder, especially SB4. Only two participants did not make a note of that, but neither of them were Volvo drivers. Other possible events were information, door open, and SB3 announced to three participants ex- pressly that the driver had forgotten to take some action.

Even if the FCW sounds were understood as different kinds of collision warnings and lane departure warnings, they were easily interpreted as warnings of a dangerous situation.

4.2 Question 2 - Which degree of warning do you think the sound belongs to?

The most outstanding category in this question was Warning High. The FCW4, which was thought of as the most suitable in a Volvo and the least

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scary, was the hardest of the FCWs to categorize. But still only two participants guessed on something other than WH. FCW1 and FCW2 had 100%

correct guesses. No one marked a sound as WH when it was not (figure 1). All the chimes were short, fast, loud and continuous.

Figure 1: Diagram showing the result of the categorization of the chimes.

According to the Volvo sound strategy 1.4 the Parking Brake is a Warning Low, but in the latest version it is a reminder. The existing chime was indeed without exception classed as a reminder, probably because of its continuity. Only PB1, which also had the highest mean value in the question about appropriateness to the sound category, was judged by scarcely half of the group as a WL. It was the most clearly dissonant and slowest, but still short, of the created PB chimes. PB1 was similar to PB2 in its dissonance and sound type. The difference between them were mainly that frequency and speed was higher in PB2, which seems to effect the comprehension of that chime as information or reminder. PB3 and Info4 seemed to be caught as quite alike. They both were little melodies of three notes, which in the ears of the participants were connected to information.

At least half of the participants placed the information chimes in the information category. The participants were actually unanimous about Info4’s category. The unanimity might be because of the similarity with information chimes in computers or public places like a train station.

The categorization of Info1 and Info3 looked almost the same. It seems like two short notes of the same frequency have the effect of sounding

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more urgent than for instance the sound of Info2, so Info1 and Info3 were therefore marked as WLs.

The seat belt reminder chimes were over all marked as reminders. The existing seat belt reminder was recognized as a reminder of everyone except one. SB1 had higher frequencies and a more bell-like sound, which might have influenced to put it as an information. SB2 was more dull, compared to SB1, contained lower frequencies and a higher percentage judged it as a reminder.

4.3 Question 3 - Premium

The questionnaire and also the answers of the participants were written in Swedish. The words used to describe sound in the answers to question 3-4 have been compiled and translated by the author and can be found in table 4.

In the opinion of the participants a premium sound was comfortable, soft, clean and round. Some wanted it to be musical with more than one note, some did not. Some wanted it to be something like a sound from a computer, some did not. The opinions were there clearly splayed.

But the opinions were rather unanimous about what was not a premium sound namely harsh, hollow, angular, sharp, annoying, flat, boring, large dynamics and beepy (figure 2).

Figure 2: Scheme of the words describing "Premium".

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Table 4: Compilation of the participants’ words to describe sound.

Swedish English (translation)

Aggresivt Aggressive

Alarmerande Alarming

Kantigt Angular

Irriterande Annoying

Uppmärksammande Attract attention

Pipigt Beepy

Tråkigt Boring

Rent Clean

Tydligt Clear

Behagligt Comfortable

Kontinuerlig Continuous

Distinkt Distinct

Platt Flat

Skrämmande Frightening

Luddiga toner Fuzzy notes

Hårt Harsh

Ihåligt Hollow

Snällt Kind

Stor dynamik Large dynamics

Starkt Loud

Melodiskt Melodic

Tyst Quiet

Igenkännlig Recognizable

Runt Round

Säkert Secure

Skarpt Sharp

Skränigt Shrill

Enkelt Simple

Mjukt Soft

The ranking of the sounds in the preference of Premium shows that SB1 was significantly higher graded than PB2 (figure 3). Interestingly they share the same synth tone. SB1 and PB2 had similar sharpness values but differ considerably in tonality and roughness. SB1 had 1.1 ton/tu. and 4 R/asper compared with PB2’s 0.7 ton/tu. and 14 R/asper (table 3), which seems to be experienced as more aggressive and therefore less premium.

The following is not statistically significant but might point to something interesting. PB2 and Info1 had the lowest mean-values, but the reason seems to differ. PB2 was disliked probably because of its roughness. Info1 had low roughness value but the sound of a flute. Like the listening test on tones, it was not appreciated as a premium sound. Roughness ap-

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Figure 3: Plot of the grade of "premium" for Parking brake, Information and Seat belt chimes.

peared to be important also in the four chimes with highest means. They shared the low roughness values, even if they were different in tone and note character. They had also the highest values of tonality.

4.4 Question 4 - Appropriateness to the sound category and in a Volvo

The information, the parking brake and the seat belt chimes had this in common, they should all be soft and attract attention, according to the participants (figure 4). The information chime should be simple, melodic and recognizable from other electronic devices like computers and tele- phones. The parking brake chime should be continuous, which also goes for the seat belt reminder. But the latter should have a dedicated sound.

These three categories of chimes should not be frightening, aggressive, loud, quiet, harsh or shrill. The parking brake chime should furthermore not sound like the seat belt reminder.

The participants expressed that the most deviant chime, the FCW, should be loud, clear, fast, alarming and not frightening. On the other hand it should not be kind, fuzzy notes, to loud or to quiet.

FCW4 is significantly higher graded than FCW2 and FCW3 in the question of suitability in a Volvo (figure 5). Some spoken comments on what

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Figure 4: Scheme of the words describing the sound for each category.

and "reveille".

Figure 5: Plot of the grade of suitability in a Volvo for Forward Collision Warnings.

Similar words to those that described how a Premium sound should be, was also used to describe how a Volvo should sound. It should also be melodic, clear, secure, distinct and everyone should understand it. It should not be a melody nor a monotone or annoying sound (figure 6).

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Figure 6: Scheme of the words describing the sound in a Volvo.

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5 Discussion

The questionnaire contained qualitative questions, which were put together. But there were also questions of quantitative character. Pairwise comparisons were considered but since grades on the chimes were desirable the Volvo-scale, which is known and often used at Volvo, was used in this work.

The choice of words in question number two is maybe a bit misleading.

"Grade of warning" could give a false idea that the different words or categories is like a stepwise warning like a grade 1 to 4. But they are divided in these groups because of how fast the driver has to give response. A better expression could have been "warning category".

The categories in the same question as above, were not explained to the test participants. So it was in the eye (ear) of the beholder to judge whether a chime that sounds like a seat belt reminder really is a reminder or a Warning Low. This of course effects the result.

All the participants were employees at Volvo Car Corporation, which could be inappropriate. The results indicate that even in such a group the opinions are various.

The sounds were randomized in the first three questions to avoid any kind of side effects. Because of a mistake, remaining chimes were not randomized. Every participant listened to the chimes in the same order.

The risks of fatigue factors and training effects are very small as there were 16 different chimes and only four chimes at a time to listen to in every category and they had already been heard in the previous tasks but in a different order. Order effects on the other hand might be present.

5.1 The future

To get a better idea about the chimes, they ought to be implemented and tested in a live situation. The opinions may be different than in this trial.

It would also be interesting to measure reaction and response time.

When a premium sound is found the following questions could lead the

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progress ahead. What kind of equipment is required to achieve a premium sound? Can the ones used today handle frequencies as low as 380 Hz? Is it desirable to make it possible for the user to personalize the chimes?

Humans have the possibility of hearing direction of the sound source. To make information in the car as clear as possible this quality should also be utilized. A seat belt reminder should not be heard just by the driver but by the passenger that has no seat belt fastened. The sound concerning the parking brake should sound as if it comes from the parking brake.

This is already dealt with in films and computer games. That stereo or surround effect has been used for several decades in music mixing. Since the technical development is heading forward and more complex sounds like music are possible to implement in the car, it should be considered and explored. But it must be taken into account that different people do not have the same ability to catch musical changes.

Speech is also an interesting field to study more. Speech alone and speech combined with chimes. We are used to the human voice and react fast to it.

There are many ways to change a sound and a small change can make a big difference.

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References

Baldwin, C. L. & Struckman-Johnson, D. (2002), ‘Impact of speech presentation level on cognitive task performance: implications for audi- tory display design’, Ergonomics 45:1, 61–74.

Belz, S. M., Robinson, G. S. & Casali, J. G. (1999), ‘A new class of auditory warning signals for complex systems: Auditory icons’, Human Factors 41:4, 608–618.

Davidsson, S. & Fagerström, M. (2007), Volvo sound strategy 1.4.

Edworthy, J., Loxely, S. & Dennis, I. (1991), ‘Improving auditory warning design: relationship between warning sound parameters and per- ceived urgency.’, Human factors 33(2), 205–232.

Edworthy, J. & Stanton, N. (1995), ‘A user-centred approach to the de- sign and evaluation of auditory warning signals: 1. methodology’, Er- gonomics 38:11, 2262–2280.

Fagerlönn, J. (2007a), Expressive musical warning signals., in ‘ICAD 2007 - The 13th International Conference on Auditory Display’, Interna- tional Community for Auditory Display.

Fagerlönn, J. (2007b), Informative auditory warning signals: a review of published material within the HCI and auditory display communities., in ‘Proceedings of the 39th Nordic Ergonomics Society Conference, 1-3 October 2007, Lysekil, Sweden’, Nordic Ergonomics Socitety.

Gaver, W. W. (1993), ‘What in the world do we hear? an ecological ap- proach to auditory source perception.’, Ecological perception 5(1), 1–

29.

Guillaume, A., Pellieux, L. & Drake, C. (2003), ‘Judging the urgency of nonvocal auditory warning signals: Perceptual and cognitive pro- cesses’, Journal of experimental psychology: Applied 9:3, 196–212.

Haas, E. C. & Casali, J. G. (1995), ‘Perceived urgency of response time to multi-tone and frequency-modulated warning signals in broadband noise’, Ergonomics 38:11, 2313–2326.

Hellier, E. J., Edworthy, J. & Dennis, I. (1993), ‘Improving auditory warning design: Quantifying and predicting the effects of different warn- ingn parameters on perceived urgency’, Human factors 35(4), 693–706.

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Keller, P. & Stevens, C. (2004), ‘Meaning from environmental sounds:

Types of signal-referent relations and their effect on recognizing au- ditory icons’, Journal of experimental psychology: Applied 10:1, 3–12.

Lemmens, P. M. C., Bussemakers, M. P. & de Haan, A. (2001), Effects of auditory icons and earcons on visual categorization: the bigger picture, in ‘Proceedings of the 2001 International conference on auditory dis- play, Espoo, Finland, July 29-August 1, 2001’, International Community for Auditory Display.

Liu, Y.-C. (2001), ‘Comparative study of the effects of auditory, visual and multimodality displays on drivers’ performance in advanced traveller information systems’, Ergonomics 44:4, 425–442.

Marshall, D. C., Lee, J. D. & Austria, P. A. (2007), ‘Alerts for in-vehicle in- formation systems: Annoyance, urgency and appropriateness’, Human factors 49:1, 145–157.

Marshall, D., Lee, J. D. & Austria, P. A. (2001), Annoyance and urgency of auditory alerts for in-vehicle information systems, in ‘Proceedings of the Human factors and ergonomics society 45th annual meeting - 2001’, Human factors and ergonomics society, pp. 1627–1631.

Stephan, K. L., Smith, S. E., Martin, R. L., Parker, S. P. & McAnally, K. I.

(2006), ‘Learning and retention of associations between auditory icons and denotative referents: Implications for the design of auditory warn- ings’, Human factors 48:2, 288–299.

Wiese, E. E. & Lee, J. D. (2004), ‘Auditory alerts for in-vehicle information systems: The effects of temporal conflict and sound parameters on driver attitudes and performance’, Ergonomics 47:9, 965–986.

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Appendices

A The chimes - sound files

In the printed report the chimes can be found on the CD in the back. In the pdf-document the files are available by clicking the items below.

1. Info1 19. Info1 with Background noise 1 2. Info2 20. Info2 with Background noise 1 3. Info3 21. Info3 with Background noise 1 4. Info4 22. Info4 with Background noise 1

5. SB1 23. SB1 with Background noise 2

9. PB1 27. PB1 with Background noise 2

10. PB2 28. PB2 with Background noise 2 11. PB3 29. PB3 with Background noise 2 12. PB4 30. PB4 with Background noise 2 13. FCW1 31. FCW1 with Background noise 1 14. FCW2 32. FCW2 with Background noise 1 15. FCW3 33. FCW3 with Background noise 1 16. FCW4 34. FCW4 with Background noise 1 17. Background noise 1

18. Background noise 2

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B Listening test of tones

Listening test of Tones

Age: _______ Man Woman

Do you have any hearing disorder? What kind? ________________________________

Earlier experience of listening tests? _________________________________________

The listening test will take about 5 minutes.

Thank you for your time!

Josefin Grönlund

You will now listen to four different sounds. Your task is to judge the sound by the word premium. Premium is here defined as high quality and luxury.

Mark your judgment of the four sounds (A-D) on the following pages.

Start the sounds by clicking on the letters. You may listen as many times as you need.

Then mark your opinion of the sound with a cross in the eligible square.

E.g. Put a cross in the square above the zero if you think that sound A does not sound premium at all. If you on the other hand think that sound A sounds pretty much premium, put a cross in the eligible square between five and ten.

Premium

Not at all Extremely Sound A

0 1 2 3 4 5 6 7 8 9 10

Not at all Extremely Sound B

0 1 2 3 4 5 6 7 8 9 10

Not at all Extremely Sound C

0 1 2 3 4 5 6 7 8 9 10

Not at all Extremely Sound D

0 1 2 3 4 5 6 7 8 9 10

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You will now compare the sounds, two at a time. Listen to the sounds once more, or as many times as you need. Mark with a ring the one of the pair that you think sounds the most premium.

Comparison of most ”Premium”:

A or B B or C C or D B or D A or C A or D

Comments: _______________________________________________________

________________________________________________________________

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C Plots of the acoustical quan- tities

Figure 7: Plot of acoustical quantities for FCW1.

—– Left channel- - - Right channel—– Both channels

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Figure 11: Plot of acoustical quantities for PB1.

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Figure 15: Plot of acoustical quantities for SB1.

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Figure 19: Plot of acoustical quantities for Info1.

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Figure 23: Plot of acoustical quantities for background noise 90 km/h.

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Figure 24: Plot of acoustical quantities for background noise "Start".

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D Listening test on chimes

Test of Information- and warning chimes

Age: _________ Man Woman

For how long have you had a driving license? _______________________________________

What car do you drive? _________________________________________________________

If you do not drive a Volvo: Would you consider driving a Volvo?

Yes No

Do you have any hearing disorder? No Yes What kind? ________________________

• Try to imagine the situation of driving a car and listen to the sounds.

• Follow the instructions, and follow your first feeling and answer as sincerely as possible.

• Take one page at a time.

• Tell the test leader if you want to listen to a sound once more.

• After some of the sections there are some lines where you can write down any comments you may have.

• The test will take 30-40 minutes.

Thank you for your time!

/ Josefin Grönlund

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1. What do you think the sound intends to warn or inform about?

Write what you think the sound intends to warn or inform about? Different sounds can have the same meaning. Go on to the next sound if any sound is too hard to define.

Sound A_____________________________________________________________________

Sound B_____________________________________________________________________

Sound C ____________________________________________________________________

Sound D ____________________________________________________________________

Sound E_____________________________________________________________________

Sound F_____________________________________________________________________

Sound G ____________________________________________________________________

Sound H ____________________________________________________________________

Sound I _____________________________________________________________________

Sound J _____________________________________________________________________

Sound K_____________________________________________________________________

Sound L _____________________________________________________________________

Sound M ____________________________________________________________________

Sound N ____________________________________________________________________

Sound O ____________________________________________________________________

Sound P_____________________________________________________________________

Comments: __________________________________________________________________

___________________________________________________________________________

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2. Which degree of warning do you think the sound belongs to?

Mark with a cross the degree of warning that you think the sounds (A-P) fits the best.

Information Reminder Warning low Warning high Sound A

Sound B Sound C Sound D Sound E Sound F Sound G Sound H Sound I Sound J Sound K Sound L Sound M Sound N Sound O Sound P

Comments: __________________________________________________________________

___________________________________________________________________________

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1 2 3 4 5 6 7 8 9 10

Worst practice / Very bad

Bad / Slightly worse

than average

Average

Better than average /

Good

Very good / Best practice

3.a Premium

You will now hear different sounds. Your task is to judge how well the sound matches the word Premium. Premium is here defined as luxury and quality. Pay no attention to the meaning of the sound, just listen to how it sounds. Mark your judgment with a cross in the eligible square.

Premium 1 2 3 4 5 6 7 8 9 10

Sound A Sound C Sound D Sound E Sound F Sound G Sound H Sound I Sound L Sound M Sound O Sound P

3.b What do you think makes a sound sound Premium? _______________________________

___________________________________________________________________________

3.cWhat do you think makes a sound not sound Premium? ____________________________

___________________________________________________________________________

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4.1.1.a Parking brake pulled

These four sounds announce that the parking brake is pulled. Your task is to judge how well the sound fits with the statement to the left of the grading line. Mark your judgment with a cross in the eligible square.

Sound E 1 2 3 4 5 6 7 8 9 10

Suits the sound category Suits a Volvo

Sound G 1 2 3 4 5 6 7 8 9 10

Suits the sound category

Suits a Volvo

Sound P 1 2 3 4 5 6 7 8 9 10

Sound D 1 2 3 4 5 6 7 8 9 10

4.1.1.b What do you think makes a sound suitable for announcing that the parking brake is

pulled?______________________________________________________________________

___________________________________________________________________________

4.1.1.c What do you think makes a sound not suitable for announcing that the parking brake is

pulled?______________________________________________________________________

___________________________________________________________________________

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4.1.2.a Information

These four sounds announce that there is information to read. Perform this section in the same way as section 4.1.1.a.

Sound A 1 2 3 4 5 6 7 8 9 10

Sound I 1 2 3 4 5 6 7 8 9 10

Suits a Volvo

Sound L 1 2 3 4 5 6 7 8 9 10

Sound F 1 2 3 4 5 6 7 8 9 10

4.1.2.b What do you think makes a sound suitable for announcing that there is available

information?__________________________________________________________________

___________________________________________________________________________

4.1.2.c What do you think makes a sound not suitable for announcing that there is available

information?__________________________________________________________________

___________________________________________________________________________

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4.1.3.a Seat belt reminder

These four sounds announce that the seat belt is not fastened. Perform this section in the same way as section 4.1.2.a

Sound C 1 2 3 4 5 6 7 8 9 10

Sound H 1 2 3 4 5 6 7 8 9 10

Suits a Volvo

Sound M 1 2 3 4 5 6 7 8 9 10

Sound O 1 2 3 4 5 6 7 8 9 10

4.1.3.b What do you think makes a sound suitable as a seat belt reminder? ________________

___________________________________________________________________________

4.1.3.c What do you think makes a sound not suitable as a seat belt reminder? _____________

___________________________________________________________________________

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4.1.4.a Forward collision warning

These four sounds announce forward collision warning. Perform this section in the same way as section 4.1.3.a.

Sound J 1 2 3 4 5 6 7 8 9 10

Suits the sound category Suits a Volvo Frightening Attract attention

Sound N 1 2 3 4 5 6 7 8 9 10

Suits a Volvo

Frightening

Attract attention

Sound K 1 2 3 4 5 6 7 8 9 10

Frightening

Attract attention

Sound B 1 2 3 4 5 6 7 8 9 10

Frightening

Attract attention

Orchestration of information and warning sounds in a car.

M A S T E R ' S T H E S I S