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Taluppfattbarhet för utrymningslarm

Pettersson, Denise LU and Lindh, Emma (2020) In LUTVDG/TVBB VBRM10 20192
Division of Fire Safety Engineering
Abstract (Swedish)
Talade utrymningslarm installeras som en riskreducerande åtgärd i byggnader där det vistas personer som inte kan väntas ha god lokalkännedom. En grundförutsättning för att utrymningslarmet ska uppfylla sin riskreducerande effekt är att det är hörbart, därav är ett talöverföringsindex, STI, på 0,55 rekommenderat. STI är ett mått på taluppfattbarhet som inte tar hänsyn till den subjektiva upplevelsen av egenskaper kopplat till det talade utrymningslarmets meddelande. Det tar inte heller hänsyn till omgivande faktorer och är väldigt beroende av lokalens utformning. Med grund i dessa egenskaper kan det ifrågasättas huruvida STI är ett tillräckligt bra mått för taluppfattbarhet i talade utrymningslarm. Vidare finns det inte mycket forskning... (More)
Talade utrymningslarm installeras som en riskreducerande åtgärd i byggnader där det vistas personer som inte kan väntas ha god lokalkännedom. En grundförutsättning för att utrymningslarmet ska uppfylla sin riskreducerande effekt är att det är hörbart, därav är ett talöverföringsindex, STI, på 0,55 rekommenderat. STI är ett mått på taluppfattbarhet som inte tar hänsyn till den subjektiva upplevelsen av egenskaper kopplat till det talade utrymningslarmets meddelande. Det tar inte heller hänsyn till omgivande faktorer och är väldigt beroende av lokalens utformning. Med grund i dessa egenskaper kan det ifrågasättas huruvida STI är ett tillräckligt bra mått för taluppfattbarhet i talade utrymningslarm. Vidare finns det inte mycket forskning inom området, och speciellt saknas det studier på vilka andra faktorer som eventuellt påverkar taluppfattbarheten i en utrymningssituation, vilket medför att det finns anledning att vidare utreda området, för att se om effekten av de talade utrymningslarmen kan förbättras eller uppnås på mer kostnadseffektiva sätt.

Syftet med arbetet är att undersöka huruvida STI är ett bra mått för taluppfattbarheten i talade utrymningslarm. Vidare är syftet att identifiera faktorer som inte tas hänsyn till i måttet STI, men som har en betydande inverkan på taluppfattbarheten, och därmed kan medföra att den önskade effekten av talade utrymningslarm inte uppnås eller försämras.

Målen för studien arbetades fram utifrån syftet och landade i följande:

• Presentera kunskapsläget kring taluppfattbarhet idag.
• Undersöka STI-värdets betydelse för taluppfattbarheten.
• Fastställa huruvida ett STI-gränsvärde generellt är lämpligt att använda för talade utrymningslarm.
• Presentera vilka andra faktorer i meddelandet som påverkar taluppfattbarheten.
• Redovisa för hur faktorer i den omgivande miljön påverkar meddelandets taluppfattbarhet.

Metoden för att utreda hypoteserna bestod av praktiska försök i form av lysningstester, både i pilot och fullskala. Pilotförsöket genomfördes på Lunds Tekniska Högskola och fullskaleförsöket genomfördes i Centrum Syd Löddeköpinge. För försöken togs följande hypoteser fram:

Hypotes 1 En kvinnlig röst uppfattas som tydligare jämfört med en manlig röst.
Hypotes 2 Typ av bakgrundsljud påverkar hur meddelandet uppfattas.
Hypotes 3 Ett meddelande på engelska uppfattas som tydligare jämfört med ett meddelande på svenska.
Hypotes 4 Omgivande faktorer har betydelse för hur ett meddelande uppfattas.
Hypotes 5 Demografiska egenskaper har en påverkan på taluppfattbarheten.

Lyssningstesterna utfördes först som ett pilotförsök för att undersöka Hypotes 1 till 3 och för att utgöra underlag för fullskaleförsöket. På så vis kunde försöket och dess parametrar bearbetas vilket möjliggjorde ett fullskaleförsök i rimlig omfattning, där Hypotes 4 undersöktes.

Totalt deltog 50 personer i pilotförsöket och 44 personer i fullskaleförsöket. Lyssningstesterna utformades med ljudfiler som försökspersonerna lyssnade på. Ljudfilerna innehöll de faktorer som tänktes kunna påverka taluppfattbareten och varierandes för de olika försökspersonerna. Dessa faktorer ligger även till grund för de framtagna hypoteserna. De olika ljudfilerna spelades upp vid olika STI-värden, för att se om parametrarnas inverkan på taluppfattbarheten blev mer eller mindre påtaglig vid ändrade värden.

I de båda försöken samlades data om objektiv och subjektiv taluppfattbarhet in genom intervjufrågor som var ställda utifrån frågeformulär. Den subjektiva datainsamlingen bestod av frågor kring svårighetsgrad och tydlighet, där försökspersonerna fick placera meddelandena på en skala samt jämföra meddelandenas parametrar. Den objektiva datainsamlingen bestod i pilotförsöket av att försökspersonerna fick skriva ner specifika siffror och ord i meddelandena, som utgjorde mätpunkter för hur stor del som uppfattades. I fullskaleförsöket bestod den objektiva mätningen av att försökspersonerna skulle upprepa meddelandet, varpå olika informationsdelar utgjorde mätpunkter. Objektivt och subjektivt insamlade data för taluppfattbarhet kunde sedan jämföras. Demografiska data samlades även in, för att undersöka dess betydelse för taluppfattbarheten.

Osäkerheter i resultaten togs hänsyn till genom sammanställning av de variationer i resultatet för de olika parametrarna som skulle undersökas. Variationerna redovisas i form av boxplotdiagram.

Utifrån studiens resultat kunde följande slutsatser och rekommendationer om taluppfattbarhet i samband med utrymningslarm ges:

• En kvinnlig röst ger bättre taluppfattbarhet jämfört med en manlig röst.
• Språkets betydelse för taluppfattbarheten har inte kunnat påvisats.
• Ett bakgrundsljud inkluderande direkt uppfattbar information påverkar taluppfattbarheten mer negativt jämfört med ett monotont bakgrundsljud med avsaknad av direkt uppfattbar information.
• Omgivande faktorer kan ha en stor negativ inverkan på taluppfattbarheten.

Studien presenterar, utifrån dess slutsatser, förslag på framtida forskning inom området. (Less)
Abstract
Voice evacuation alarms are installed as a risk mitigation measure in buildings where people reside who cannot be expected to have good local knowledge. Voice evacuation alarms have basic requirements that need to be meet such as auditability, where a speech transmission index, STI, of 0,55 is recommended. STI is a measure of speech intelligibility that does not include the subjective experience of characteristics linked to the message of the voice evacuation alarm. The measure also does not account for factors in the surrounding environment and is very dependent on the layout of the premises. Given these characteristics, it can be questioned whether STI is a sufficiently reliable measure of speech intelligibility in voice evacuation... (More)
Voice evacuation alarms are installed as a risk mitigation measure in buildings where people reside who cannot be expected to have good local knowledge. Voice evacuation alarms have basic requirements that need to be meet such as auditability, where a speech transmission index, STI, of 0,55 is recommended. STI is a measure of speech intelligibility that does not include the subjective experience of characteristics linked to the message of the voice evacuation alarm. The measure also does not account for factors in the surrounding environment and is very dependent on the layout of the premises. Given these characteristics, it can be questioned whether STI is a sufficiently reliable measure of speech intelligibility in voice evacuation alarms. Furthermore, there is a limited amount of scientific literature in the area, and in particular, there are no studies on what factors that may affect speech intelligibility in an evacuation situation, which means that there is reason to further examine the area, to survey if the effect of the voice evacuation alarms can be improved or achieved in a more cost-effective manner.

The aim of this study is to examine whether STI is a good measure of speech intelligibility in voice evacuation alarms. Furthermore, the aim is to identify factors that are not taken into account in the STI measure, but that do have a significant impact on speech intelligibility and may result in the desired effect of voice evacuation alarms not being achieved or being impaired.

The objectives of the study were constructed based on the aim of the study, which led to the following objectives:

• Present on the state of knowledge about speech intelligibility today.
• Investigate the importance of the STI value for speech intelligibility.
• Determine whether a general STI limit value is suitable for use in fire evacuation alarms.
• Present what factors in the message affect speech intelligibility.
• Examine how factors in the surrounding environment affect the speech intelligibility of the message.

To answer the objectives, the chosen method consisted of practical listening tests. A pilot test was made to provide a basis to a full-scale test. The pilot test was conducted at Lund University of Technology and the full-scale test was conducted at Center Syd Löddeköpinge. The following hypotheses were set for the listening tests:

Hypothesis 1 A female voice is perceived as clearer compared to a male voice.
Hypothesis 2 The type of background noise affects how the message is perceived.
Hypothesis 3 A message in English is perceived as clearer compared to a message in Swedish.
Hypothesis 4 Surrounding factors are important for how a message is perceived.
Hypothesis 5 Demographic characteristics have an influence on speech intelligibility.

The listening tests were first performed as a pilot test to examine Hypotheses 1 to 3 and to form the basis for the full-scale test. In this way, the experiment and its factors could be processed, which enabled a full-scale test to a reasonable extent, where Hypothesis 4 was investigated.
A total of 50 persons participated in the pilot test and 44 persons participated in the full-scale test. The listening tests were designed with audio files that the subjects listened to. The audio files contained the factors that were thought to influence speech intelligibility and varied for the different subjects. These factors also form the basis for the hypotheses developed. The different audio files were played at different STI values, to evaluate if the different factors’ influence on speech intelligibility became more or less noticeable at varied values.
In both tests, data on objective and subjective speech intelligibility were collected through questionnaires which were answered by the subjects and based on the hypothesis. The collection of subjective data consisted of questions about the severity and clarity of the audio files. The subjects were allowed to evaluate the audio files by rating them on a scale and compare the different factors of the messages. The objective data collection in the pilot test consisted of the subjects being allowed to write down specific numbers and words in the messages, which constituted measuring points for how much of the message the test subject had perceived. In the full-scale test, the objective measurement consisted of the subjects orally repeating the message, whereupon different pieces of information constituted measuring points. Objectively and subjectively collected data for speech intelligibility could then be compared. Demographic data were also collected, to examine its importance for speech intelligibility.

Uncertainties in the results were taken into account by compiling the variations in the results for the various examined factors. The variations are presented in box plot charts.
Based on the results of the study, the following conclusions and recommendations regarding speech intelligibility in voice evacuation alarms could be given:

• A female voice provides better speech intelligibility compared to a male voice.
• The importance of language for speech intelligibility has not been demonstrated.
• The background noise of directly perceivable information affects speech perception more negatively compared to monotonous background noise with the absence of directly perceivable information.
• Surrounding factors can have a major negative impact on speech intelligibility.

The study presents, based on its conclusions, suggestions for future research in the field. (Less)
Please use this url to cite or link to this publication:
author
Pettersson, Denise LU and Lindh, Emma
supervisor
organization
course
VBRM10 20192
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Taluppfattbarhet, Talöverföringsindex, Talat Utrymningslarm, Människors Beteende vid en Utrymningssituation, Utrymning, Perception av ljud, Maskeringseffekter, Lyssningstest Speech Intelligibility, Speech Transmission Index, Voice Evacuation Alarm, Evacuation, Human Behaviour in Fire, Speech Perception, Masking effects, Listening test
publication/series
LUTVDG/TVBB
report number
5603
other publication id
LUTVDG/TVBB--5603--SE
language
Swedish
id
9001462
date added to LUP
2020-01-16 11:17:37
date last changed
2020-01-16 14:08:57
@misc{9001462,
  abstract     = {Voice evacuation alarms are installed as a risk mitigation measure in buildings where people reside who cannot be expected to have good local knowledge. Voice evacuation alarms have basic requirements that need to be meet such as auditability, where a speech transmission index, STI, of 0,55 is recommended. STI is a measure of speech intelligibility that does not include the subjective experience of characteristics linked to the message of the voice evacuation alarm. The measure also does not account for factors in the surrounding environment and is very dependent on the layout of the premises. Given these characteristics, it can be questioned whether STI is a sufficiently reliable measure of speech intelligibility in voice evacuation alarms. Furthermore, there is a limited amount of scientific literature in the area, and in particular, there are no studies on what factors that may affect speech intelligibility in an evacuation situation, which means that there is reason to further examine the area, to survey if the effect of the voice evacuation alarms can be improved or achieved in a more cost-effective manner.

The aim of this study is to examine whether STI is a good measure of speech intelligibility in voice evacuation alarms. Furthermore, the aim is to identify factors that are not taken into account in the STI measure, but that do have a significant impact on speech intelligibility and may result in the desired effect of voice evacuation alarms not being achieved or being impaired.

The objectives of the study were constructed based on the aim of the study, which led to the following objectives:

•	Present on the state of knowledge about speech intelligibility today.
•	Investigate the importance of the STI value for speech intelligibility.
•	Determine whether a general STI limit value is suitable for use in fire evacuation alarms. 
•	Present what factors in the message affect speech intelligibility.
•	Examine how factors in the surrounding environment affect the speech intelligibility of the message.

To answer the objectives, the chosen method consisted of practical listening tests. A pilot test was made to provide a basis to a full-scale test. The pilot test was conducted at Lund University of Technology and the full-scale test was conducted at Center Syd Löddeköpinge. The following hypotheses were set for the listening tests:

Hypothesis 1	A female voice is perceived as clearer compared to a male voice.
Hypothesis 2	The type of background noise affects how the message is perceived.
Hypothesis 3	A message in English is perceived as clearer compared to a message in Swedish.
Hypothesis 4	Surrounding factors are important for how a message is perceived.
Hypothesis 5	Demographic characteristics have an influence on speech intelligibility.

The listening tests were first performed as a pilot test to examine Hypotheses 1 to 3 and to form the basis for the full-scale test. In this way, the experiment and its factors could be processed, which enabled a full-scale test to a reasonable extent, where Hypothesis 4 was investigated.
A total of 50 persons participated in the pilot test and 44 persons participated in the full-scale test. The listening tests were designed with audio files that the subjects listened to. The audio files contained the factors that were thought to influence speech intelligibility and varied for the different subjects. These factors also form the basis for the hypotheses developed. The different audio files were played at different STI values, to evaluate if the different factors’ influence on speech intelligibility became more or less noticeable at varied values.
In both tests, data on objective and subjective speech intelligibility were collected through questionnaires which were answered by the subjects and based on the hypothesis. The collection of subjective data consisted of questions about the severity and clarity of the audio files. The subjects were allowed to evaluate the audio files by rating them on a scale and compare the different factors of the messages. The objective data collection in the pilot test consisted of the subjects being allowed to write down specific numbers and words in the messages, which constituted measuring points for how much of the message the test subject had perceived. In the full-scale test, the objective measurement consisted of the subjects orally repeating the message, whereupon different pieces of information constituted measuring points. Objectively and subjectively collected data for speech intelligibility could then be compared. Demographic data were also collected, to examine its importance for speech intelligibility.

Uncertainties in the results were taken into account by compiling the variations in the results for the various examined factors. The variations are presented in box plot charts.
Based on the results of the study, the following conclusions and recommendations regarding speech intelligibility in voice evacuation alarms could be given:

•	A female voice provides better speech intelligibility compared to a male voice.
•	The importance of language for speech intelligibility has not been demonstrated.
•	The background noise of directly perceivable information affects speech perception more negatively compared to monotonous background noise with the absence of directly perceivable information.
•	Surrounding factors can have a major negative impact on speech intelligibility.

The study presents, based on its conclusions, suggestions for future research in the field.},
  author       = {Pettersson, Denise and Lindh, Emma},
  keyword      = {Taluppfattbarhet,Talöverföringsindex,Talat Utrymningslarm,Människors Beteende vid en Utrymningssituation,Utrymning,Perception av ljud,Maskeringseffekter,Lyssningstest Speech Intelligibility,Speech Transmission Index,Voice Evacuation Alarm,Evacuation,Human Behaviour in Fire,Speech Perception,Masking effects,Listening test},
  language     = {swe},
  note         = {Student Paper},
  series       = {LUTVDG/TVBB},
  title        = {Taluppfattbarhet för utrymningslarm},
  year         = {2020},
}