ROGER RUTH SYMPOSIUM2019 JMU

CLASSROOM ACOUSTICSTHE BASICS

Joseph Smaldino, Ph.D.

Professor Emeritus: Illinois State University; University of Northern Iowa

Adjunct Professor : UT Health Sciences Center

Adjunct Professor: East Tennessee State University

ADDITIONAL INFORMATION CONCERNING CLASSROOM ACOUSTICS

FRAMEWORK ACOUSTIC ACCESSIBILITY

• Accurate speech reception and perception are essential precursors to listening, literacy, and learning in the classroom.

• Faulty transmission of the speech signal cannot be tolerated and, if it is, it might be thought of as depriving students access to the very signal important for education – the speech signal.

THE CLASSROOM LEARNING CHAIN

TEACHER

Adequate Speech

Intensity

Complexity/Familiarity of Speech

Clarity of Speech

ACOUSTIC TRANSMISSIONENCODING CAPACITY

Status of Hair Cells

Status of Auditory Neurons

STUDENT

Speech and Language

Competency

Cognitive and Processing

CompetencyNOISE

Background Noise Level

Distance

Early and Late Reverberation

HEARING

• Sensory

• Bottom Up Process

• Perceive physical cues around us and

allow our central nervous systems to

recognize and organize these cues to

make sense of the world around us.

• Cognitive

• Top Down Process

• Depends on our cognitive abilities, the

things we know about ourselves (i.e., our

cognitive self) and the world around us,

our store of knowledge, our ability to

draw upon working (i.e., short-term) and

long-term memory (at will) to enhance

and supplement our knowledge and to

better understand things occurring at

every moment in time.

LISTENING

HEARING VS LISTENING[ B E C K & F L E X E R , 2 0 1 1 ]

WHY IT IS IMPORTANT TO CONSIDER CLASSROOM ACOUSTICS

Auditory-Linguistic-Cognitive Development

COGNITIVE CONSEQUENCES OF ACOUSTICALLY DEGRADED SPEECH

( P E E L L E . 2 0 1 7 )

CHILDREN ARE NOT ADULTS

• Children bring an immature and incomplete auditory neurological

system to listening situations-the system isn’t mature until about age

15.

• Children have limited knowledge of language and life experiences

which impairs their ability to “fill in gaps of information” i.e.: auditory

closure.

• Children have more difficulty extracting speech from noise i.e.: figure–

ground.

CHILDREN ARE NOT ADULTSBEC AUSE OF IMMATURE AUDITORY-L INGUIST IC -COGNIT IVE

BRA IN DEVELOPMENT

• Children require more complete and detailed auditory information

than adults.

• As compared to normal-hearing adults, all children need a quieter

listening environment and a louder primary signal (up to a +15 SNR)

to create new neural maps and to develop their auditory-linguistic-

cognitive brains.

CHILDREN ARE NOT ADULTS

CASCADING EFFECTS OF FAULTY ACOUSTIC ACCESS FOR CHILDREN

• Fragmented hearing

• Increased listening effort

• Decreased listening comprehension

• Increased fatigue from listening/processing

• Slower pace of learning

(Anderson, 2014 )

ACOUSTIC ACCESSIBILITY IS A GOOD THING

• Improved academic achievement,

especially for younger students

• Decreased distractibility and increased

on-task behavior

• Increased attention to verbal instruction

and activities and improved

understanding

• Decreased number of requests for

repetition

• Decreased frequency of need for verbal

reinforcers to facilitate test performance

• Decreased test-taking time

• Improved spelling ability under degraded

listening conditions

• Increased sentence recognition ability

• Improved listening/reading test scores

• Increased language growth

• Improved student voicing when speaking

• Increased student length of utterance

• Increased confidence when speaking

• Improved ease of listening and teaching

• Reduced vocal strain and fatigue for

teachers

• Increased mobility for teachers

• Reduced special education referral rate

WHO IS AT RISK

• As compared to normal-hearing adults, all children

need a quieter listening environment and a louder

primary signal.

• Children with temporary or permanent hearing loss

• Children with English as a second language

• Teachers

BACKGROUND NOISE

SIGNAL TO NOISE RATIO

BARRIER TO ACOUSTIC ACCESSIBILITY SIGNAL-TO-NOISE RATIO

• Level of the speaker’s

speech

• Distance from speaker

to listener

• Level of speech-

interfering noise—the

background noise level

(Smaldino and Crandell, 2004)

BARRIER TO ACOUSTIC ACCESSIBILITYREVERBERATION

• RT60

• Time it takes for a signal to decrease 60 dB

• Frequency dependent

• Highest in the lowest frequencies

REVERBERATIONCAN BE GOOD BUT MOSTLY BAD

(Smaldino and Crandell, 2004)

NOISE/REVERBERATION OCCUR SIMULTANEOUSLY

RAPID SPEECH TRANSMISS ION INDEX (RASTI )

NOISE/REVERBERATION OCCUR SIMULTANEOUSLYRAPID SPEECH TRANSMISSION INDEX (RASTI)

Location RASTI average

Row 1 FRONT .79

Row 2 .71

Row 3 .68

Row 4 .66

Row 5 .65

Row 6 .62

Row 7 BACK .58

REFERENCE 1.0

Adapted from Leavitt and Flexer, 1991

ANSI/ASA 12.60-2010

Acoustical Performance Criteria, Design Requirements, and

Guidelines for Schools. Part 1: Permanent Schools

Available for free at

http://asastore.aip.org

• The one-hour average A-

weighted background noise

level cannot exceed 35 dB

(55 dB if C-weighting is

used).

• For averaged size

classrooms, the reverberation

time (RT60) cannot exceed

0.6 seconds but 0.4 seconds

if hearing impaired children

are in room.

WHY PREFERENTIAL SEATINGCRITICAL DISTANCE

CRITICAL DISTANCE (FEET)

Up to and including this distance from the talker, reflections from the sound reverberating in the

room will enhance the speech signal; beyond this distance the speech signal will be degraded by the

later reflections of the sound reverberations.

(adapted from Boothroyd with permission)

Room

Volume

RT

.3

RT

.4

RT

.5

RT

.6

RT

.7

RT

.8

RT

.9

RT

1.0

2000 ft3 5.2 ft 4.5 4.0 3.7 3.4 3.2 3.0 2.8

4000 7.3 6.3 5.7 5.2 4.8 4.5 4.2 4.0

6000 8.9 7.7 6.9 6.3 5.9 5.5 5.2 4.9

8000 10.3 8.9 8.0 7.3 6.8 6.3 6.0 5.7

10,000 11.5 10.0 8.9 8.2 7.6 7.1 6.7 6.3

12,000 12.6 11.0 9.8 8.9 8.3 7.7 7.3 6.9

14,000 13.7 11.8 10.6 9.7 8.9 8.4 7.9 7.5

16,000 14.6 12.6 11.3 10.33 9.6 8.9 8.4 8.0

18,000 15.5 13.4 12.0 11.0 10.1 9.5 8.9 8.5

20,000 16.3 14.1 12.6 11.5 10.7 10.0 9.4 8.9

TYPICAL CLASSROOM BACKGROUND NOISE

[ K N E C H T . , N E L S O N , W H I T E L A W , & F E T H , 2 0 0 2 ]

TYPICAL CLASSROOM REVERBERATION

[ K N E C H T . , N E L S O N , W H I T E L A W , & F E T H , 2 0 0 2 ]

ACOUSTICS OF OLD AND NEW SCHOOLS( N E L S O N , S M A L D I N O, E R L E R & G A R S T E C K I , 2 0 0 7 )

HOUSTON WE HAVE A CLASSROOM ACOUSTICS PROBLEM

COMPLIANCE WITH CLASSROOM ACOUSTIC STANDARDS

• Incorporated into the Green Building Code.

• International Building Codes Council [A117.1].

• Adopted classroom acoustics model building code standard.

• Closely parallels performance criteria of ANSI/ASA S12.60-2010/Part 1.

• Code is ready for adoption by school districts, localities and states.

CREATING DESIRABLE ACOUSTICSOBSERVATIONAL SURVEY

• Designed to identify acoustical problems that may interfere with communication and instruction

• Identify acoustics that may interfere with the performance of a Classroom Audio Distribution System (CADS)

• Identify rooms for a comprehensive acoustic analysis and acoustic interventions

BACKGROUND NOISEOBSERVATIONAL SURVEY

CLASSROOM OBSERVATION YES NO

Audible heating and ventilation system

Equipment must be turned off during

instruction

Exterior noise audible during instruction

Internally generated noise during

instruction (aquarium air pump, student

activities)

A “YES” response indicates the room probably requires a

more in depth evaluation.

REVERBERATION OBSERVATIONAL SURVEY

CLASSROOM OBSERVATION YES NO

Hard surface ceiling without acoustic tiles

Ceilings are higher than 11 feet

Ceiling tiles are present but painted over

Floor constructed of hard reflective

material like wood or tiles

Walls constructed of hard reflective

material like plasterboard or cement

blocks

A “YES” response indicates the room probably requires a

more in depth evaluation.

OBSERVATIONAL SURVEYITS NOT ROCKET SCIENCE

Identification of acoustic problems can be simple. Stand in

the instructional area of the classroom, close your eyes, and

listen to words read aloud. If some of the words are not

heard clearly or correctly, the room probably requires a

more in depth acoustic evaluation.

CREATING DESIRABLE ACOUSTICS MAKE ACTUAL ACOUSTIC

MEASUREMENTS

• We would like to understand the acoustics of the rooms in which our clients are

using hearing aids to help us make technology decisions.

• Knowledge of room acoustics may help inform us of the need for hearing assistive

devices (HATs) or classroom audio distribution systems (CADS).

• We could determine the effectiveness of physical room interventions.

• We might like to predict how intelligible speech would be in specific acoustic

environments (Speech Transmission Index family of measurements).

• We might like to determine the appropriateness of a noise spectrum for everyday

living activities (Noise criteria curves).

• And of course, determine compliance with ANSI classroom Standard.

SOUND LEVEL METER REQUIREMENTS AND RECOMMENDATIONS

• Type 2 general purpose meets (ANSI S1.4-1983)

• Slow meter response: typically used for noise measurements

• Octave or 1/3 octave filters

• Integrating: capable of averaging SPL/time

• A and C weighting networks

• RT time capable

• OFTEN EXPENSIVE, BULKY AND HAS A LEARNING CURVE AND REQUIRES EXPERIENCE: as a result audiologists frequently do not have access to the necessary measurement instrumentation.

“THE TIMES THEY ARE A-CHANGIN’

…….and technology has made it possible and inexpensive enough for each

and every hearing professional to be able to make acoustic measurements and

screen for classroom acoustic adequacy…..here is how

A TUTORIAL YOU MAY FIND INTERESTING

Ostergren, D. and Smaldino, J. (2012).

Technology in educational settings: It may

already be in your pocket or purse. Journal of

the Educational Audiology Association, 18.

SMART PHONE APPLICATIONS

WHAT IF YOU ARE AT A BIRTHDAY PARTY AND FIND YOURSELF SHORT OF BREATH?

YUP…THERE IS AN APP (IBLOWER)

DID YOU EVER DESIRE A COOL BEER BUT DID NOT HAVE ACCESS TO ONE ?

THERE’S AN APP FOR THAT! (IBEER)

OR HOW ABOUT YOU WANTING TO KNOW IF A WATERMELON OR

PUMPKIN IS RIPE?

THERE IS AN APP FOR THAT TOO! (IWATERMELON)

OR…LET ME SEE….SAY YOU WANTED TO MEASURE ANSI PERFORMANCE

CRITERIA FOR CLASSROOM ACOUSTICS OR WANTED TO MEASURES THE

ACOUSTICS OF A ROOM?

YOU’RE IN LUCK…THERE IS AN APP FOR THAT TOO (AUDIOTOOLS)

POSSIBLE APPSIOS OR ANDROID

• Few appear to be designed by audio professionals

for use by professionals (equivalent to type 2 SLM)

• Others seemed to be designed for estimation or

amusement purposes, lacking features like A-

weighting, spectral analysis, reverberation time,

fast/slow response time, etc.

A USEFUL APPLICATIONAUDIO TOOLS

• Apple iOS because of the high market penetration of these

products

• AudioTools app bundle by Studio Six Digital because it is one

of the most sophisticated and cost-effective programs

available

• Sound level meter

• Impulse response to determine RT60

• http://studiosixdigital.com/audiotools/

SOUND LEVEL METER

CALIBRATION

IAUDIOINTERFACE/PISTON PHONE

TRIMMING OF APPLICATION

SELF-CALIBRATING ITESTMIC

• When you plug iTestMic into any iOS device running

AudioTools, the factory calibration values are read and

applied, giving you an instantly available accurate SPL

measurement tool calibrated to +/-0.1 dB, no matter what

iOS device you are using.

REVERBERATION TIME MEASUREMENT USING IMPULSE RESPONSE

IMPULSE RESPONSE

IMPULSE RESPONSE/RT 60

IMPULSE RESPONSE

C50- ratio of early (0-50 ms) to late (50 ms to end) – aligned with speech perception

C80 ratio of later (0-80 ms) to late (80 ms to end) – aligned with music perception

OTHER USEFUL AUDIO TOOLSSPL GRAPH AND DATA SHARING

OTHER USEFUL AUDIO TOOLSREAL TIME ANALYZER

» Note the noise criteria curves

PROFESSIONAL ROLES OF AUDIOLOGISTS

• Evaluate Room Conditions

• Acoustic performance

• Behavioral performance

• Recommend modifications

• Classroom modifications

• SNR enhancement technology

• Audio Distribution System

• Personal FM

• Verify Acoustic Efficacy

• Verify Behavioral Efficacy

• (Re)Habilitation

• Advocacy

• Education

CREATING DESIRABLE ACOUSTICS RECOMMENDATIONS PHYSICAL INTERVENTIONS

• Optimizes benefit from other interventions

• Reduces pathways for noise interference

• Reduces sources of noise interference

• Reduces classroom reverberation

• Intervention is on a cost continuum

• New construction

• Existing construction

See Crandell & Smaldino in Crandell, Smaldino and Flexer (2005) for

practical suggestions for reduction of classroom noise levels and

reverberation.

CREATING DESIRABLE ACOUSTICS TECHNOLOGICAL RECOMMENDATIONS

• Classroom Audio Distribution System (CADS)

• FM, infrared, loop

• Advanced signal processing schemes

• Roger

• Advanced loudspeaker technology

• Array and Bending Wave

• Personal SNR enhancement

• FM systems and/or hearing aids

• Advanced signal processing (noise and reverberation reduction)

• Speech enhancement schemes

• Close proximity (desktop) CADS

OUTCOME MEASURES

• Pre and Post background noise and reverberation measurements

• Some speech recognition measures• (NEED SENSITIVE TEST IN NOISE FOR CHILDREN)

• QSIN-BKB version (6+)

• HINT-C (5+)

• Blair sentences

• Behavioral performance measures

• Functional listening

• “On-task” behavior

• Listening Inventories for Education – Revised

• SIFTER

• Achievement test scores

• General, reading, spelling, literacy

The importance of desirable acoustics for auditory-

linguistic-cognitive brain development and

classroom listening and learning cannot be

overstated. It behooves each and every hearing

professional to advocate for good classroom

acoustic environments.

THANK YOU

He taught us to become stronger,

smarter, kinder, better…

Carl Crandell, teacher and scholar

WE’VE GOT CLASSROOM ACOUSTICS ….IN OUR HANDS

WE’VE GOT EXPLAINING ACOUSTIC BRAIN DEVELOPMENT …. IN OUR HANDS

WE’VE GOT UNDERSTANDING BARRIORS TO LISTENING AND LEARNING …. IN OUR HANDS

WE’VE GOT CLASSROOM ACOUSTICS ….IN OUR HANDS

WE’VE GOT UNDERSTANDING THE IMPACT OF BACKGROUND NOISE…. IN OUR HANDS

WE’VE GOT KNOWING THE GOOD AND BAD OF REVERBERATION …. IN OUR HANDS

WE’VE GOTEXPLKAINING THE ANSI CLASSROOM ACOUSTIC STANDARD …. IN OUR HANDS

WE’VE GOT CLASSROOM ACOUSTICS ….IN OUR HANDS

WE’VE GOT LOOKING FOR UNDESIRABLE CLASSROOM ACOUSTICS ….IN OUR HANDS

WE’VE GOT CHOOSING AN APPROPRIATE MEASUREMENT APP….IN OUR HANDS

WE’VE GOT COMPARING MEASUREME4NTS TO ANSI STANDRDS… IN OUR HANDS

WE WE’VE GOT CLASSROOM ACOUSTICS ….IN OUR HANDS

WE’VE GOT IMPROVING CLASSROOM ACOUSTICS…. IN OUR HANDS

OH YEA ……. BIG IMPROVEMENTS IN ACOUSTICS…. IN OUR HANDS (louder)…

COME ON NOW….(slower)…WE’VE GOT CLASSROOM ACOUSTICS… IN OUR HANDS