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Re: [AUDITORY] Hearing loss criteria for older adults

Dear Arley,

There is a very precise way to control for the audibility of sound.  Useful for both screening the potential subjects, as well as calculating how much you may need to increase the sound level to make it audible.  
This procedure forms one of the the basics of the SII protocol (ANSI S3.5 1997) and it is discussed in detail in the article Pavlovic, C.V. "Derivation of primary parameters and procedures for use in speech intelligibility predictions," JASA 1987.   The article and the standard are relatively complex, and you may want to resort to the following procedure where the goal is to see where on the average across time the sound is below or above threshold.  If you are dealing with short impulsive stimuli the accuracy of the procedure may be compromised.  

A. In Table 4 of the Standard locate "Reference Internal Noise Spectrum Level" for octave frequencies between 250 and 8000 Hz.  These values correspond to 0 dB HL.    Call this value A.
B.  Measure for each of the octaves the average dB SPL for your environmental sounds using a sound level meter at the position of the listener with the listener absent.  Call this value B.  (B-A is now how much the sound is above the normal threshold). 
C. Measure for each octave frequency the hearing loss of the person using an audiometer.  If the test you are doing is for binaural listening and the sound is in front, use the better ear threshold.  If the thresholds are identical decrease the threshold you measured by 2 dB. If the sounds are coming from all around the listener I strongly suggest you limit the test to symmetrical hearing loss only and do not use the 2 dB correction.  Call this value C. 

When you have these three values for each octave frequency, then the level of the Signal relative to the Actual Threshold is;  (B - A) - C = B - A - C. 

For example at 1000 Hz:

You will find in the Table 4, that the internal noise that corresponds to 0 dB HL is:  A = -12.5 dB SPL
You measure the environmental signal to be B = 25 dB SPL 
You measure the Left and Right  ear thresholds to be 30 dB HL.  Since they are identical, you will take the binaural threshold C = 30-2 = 28 dB HL

Now, B - A - C =  25 + 12.5 - 28 = 9.5 dB (not dB SPL).  That is the Sound is 9.5 dB above the threshold.  

Normally, the sound is variable, and you may want some estimate of that variability as well.


Best of luck.

Chas

Chas (Caslav, Chaslav) Pavlovic





On Dec 3, 2017, at 17:36, Elaine Saunders <elaine.saunders@xxxxxxxxxxxxxxxxxxxxx> wrote:

Alternatively, use something like the Blamey Saunders SPT - ie speech perception 
Elaine

On 2 December 2017 at 00:32, Christine Rankovic <rankovic@xxxxxxxxxxxxxxxx> wrote:

Hi Arley:

 

This is an excellent question.  I don’t know of any printed guidelines. 

 

Not all older listeners have hearing loss, therefore you could include only those older listeners with normal hearing.  Or, you can have TWO groups of older listeners:  one with normal hearing and one with mild hearing loss.  In your study, I would recommend the latter due to your anticipation of audiogram effects.

 

Also, beware that anyone that has thresholds at or just over 25 dB HL at more than a few audiometric test frequencies actually has significantly reduced hearing ability, even though that is a standard audiometric cutoff.  Audiologists realize this, but non-audiologists usually don’t.  Try listening yourself with those little foam plugs in your ears.  With those plugs, you probably still have hearing better than 25 dB at all frequencies but maybe you have 15-20 dB of loss at low frequencies.  You’ll find that it is very difficult to function with them in place.  A better cutoff rule for your experiment might be something like:  All normal-hearing listeners had audiometric thresholds within the normal range with the restriction that, for any individual listener, thresholds at no more than two test frequencies were permitted to exceed 20 dB HL.

 

I hope this is helpful.

 

Christine Rankovic

 

 

From: AUDITORY - Research in Auditory Perception [mailto:AUDITORY@LISTS.MCGILL.CA] On Behalf Of Arley Schenker
Sent: Thursday, November 30, 2017 2:26 PM
To: AUDITORY@xxxxxxxxxxxxxxx
Subject: Hearing loss criteria for older adults

 

Dear Auditory List,

 

I am a master’s student working under Andrea Halpern at Bucknell University. We are running some auditory imagery studies with older (60-85 years) adults, and we are using audiometry to screen their hearing. Some of the environmental sounds we are asking participants to imagine involve somewhat high frequencies.

 

I understand that pure tone averages greater than 25 dB HL are considered to characterize hearing loss; however, as some hearing loss is expected with aging, I am wondering whether anyone can point me to some best practices or suggestions regarding the inclusion of older adults with slight hearing loss. It's not a psychophysical study, but the participants do need to be able to hear and imagine the sounds reasonably accurately.

 

Thanks in advance for your help,

Arley Schenker




 




--
 
Dr Elaine Saunders BSc MSc(ClinAudiol) PhD GAICD GradDipMgt(Tech)
Adjunct Professor, Faculty of Science, Engineering & Technology, Swinburne University


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