loudness Flashcards
intensity discrimination
which has higher intensity?
you can tell a half dB apart.
weber’s law
DELTA I / I = k
The size of the just noticeable difference (i.e., delta I) is a constant proportion of the original stimulus value.
Restated: The change in a stimulus that will be just noticeable is a constant ratio of the original stimulus
loudness
subjective matter. loudness is like pitch where freq discrimination is like intensity discrim.
Loudness corresponds to the subjective impression of the magnitude of a sound.
Formal definition of loudness: that attribute of auditory sensation in terms of which
sounds can be ordered on a scale extending from quiet to loud (ANSI, 1994).
phons
The level of a 1000-Hz tone in dB SPL that equals the loudness of a test sound.
if an electric motor is equal in loudness to a 1000-Hz tone at 65 dB SPL, the motor has a loudness of 65 phons.
2 methods to measuring phons
Method 1: Adjust the level of the 1000-Hz tone (shown in A) to equal the loudness of the test tone (shown in B).
Method 2: Adjust the level of the test tone (shown in B) to equal the loudness of the 1000-Hz tone (shown in A).
equal loudness contours
x axis= freq, y axis = sound level dB SPL.
tells you for all of the diff freq, what the phon level is.
By definition,
the loudness in phons at 1 kHz, is the same as the SPL at 1 kHz.
loundness summation
Doesn’t get louder right away,
Beyond critical bandwidth, (gets wider) loudness increases.
Implication of things that determine loudness: as the bandwidth gets wider, you engaging more auditory filters. So theres the 1 centered on the narrow band but now as we go wider we add another critical band. And then we go wider and another gets added on. So what is going with loudness? Does the system care? No. as youre getting wider the idea is that the loudness system is paying attention to how many critical bands are actually engaged.
loudness scaling: sones
One sone is arbitrarily defined as the loudness of a 1000-Hz tone at 40 dB SPL.
Example: a sound has a loudness of 2 sones if it is judged to be twice as loud as a 1000-Hz at 40 dB SPL
method for measuring sones
Magnitude estimation: sounds with various intensities are presented and the listener assigns a number to each according to its perceived loudness.
10dB change in sound level is a doubling in loudness ((rule to remember))
loudness recruitment
Abnormal growth of loudness associated with hearing loss
Limits the dynamic range, because sounds near threshold sound soft, but more intense sounds sound as loud as in normal hearing
loudness recruitment graph
x=level of fixed tone dB SPL; y =level of matching tone dB SPL:
Here is the concept: 2 ears. 1 ear is normal and one isn’t. they’re judging loudness between the 2 ears. You have a fixed tone in 1 ear and match that tone in the other ear. If you have a 50dB tone should be matched to 50. the dotted line is what normal loudness looks like. On the other hand if you have a hearing loss in one of these ears and youre tryign to match it…you can present a tone of 60dB and you match it to 30dB. Their perception is that its 30dB even tho its 60dB. How does this happen? If they cant hear very well you cant play a 30dB tone if they have a 60dB loss! (just for an easy example). Once you can finally hear it at 60dB its soft (like a normal hearing person would have heard the 30dB tone from the beginning).
Dynamic range is from the lowest thing they hear to the highest thing. The range over which their experieence is varying is the dynamic range. Here is 60dB for the normal. The dark line has a dynamic range to 50dB dynamic range by a 30dB tone range.
Hearing impaired have smaller dynamic range. Also, at low sound levels their own threshold will be very soft, but at the high sound levels the loudness is equal or very similar to normal hearing. Even with a hearing loss, loud things sound very loud.
Dynamic is y axis and stimulus is x axis
temporary threshold shift (TTS)
temporarily have a hearing loss, thresholds increase temporarily
higher thresholds as exposure time increases
losses are at freq higher than at the exposure tone a 1/2 octave shift.
basalward shift of max vibration in BM as intensity increases which means the damage will be more towards the base
Hearing level (HL)
Thresholds specified relative to 0 dB HL, the average threshold at each frequency for young healthy listeners with “normal” hearing
half octave shift (Davis)
The more noise youre exposed to the worse your threshold gets.
Its also spread over frequencies.
Integrate this information with summation information.
The hearing loss is not at the freq where you have to be exposed…its at a higher frequency.
Sooo it turns out that ½ octave above the given signal is where the loss is. 2000hz freq given…3000hz damaged.
So people don’t notice their hearing loss because its not affecting their speech perception. Its insidious because this loss happens a lot but we don’t notice it.
long term consequence of TSS
hearing thresholds recover. Time after noise exposure 1 and 3 days: significant hearing loss 2 weeks: hearing back to normal 8 weeks: normal hearing maintained hair cell response returns to normal synaptic loss doesn't recover neural amplitude loss doesn't recover ganglion 8th nerve cell loss significantly delayed
permanent hearing loss
As you get older you lose more and at high frequencies
Because of ½ octave shift
