Hear Things: Frequency, Vibration & Audibility

  • Context: High School 
  • Thread starter Thread starter toesockshoe
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Discussion Overview

The discussion revolves around the audibility of sound frequencies, specifically focusing on the lower limit of human hearing, the relationship between string vibrations and sound production, and individual variations in hearing sensitivity. Participants explore concepts related to frequency perception, including the nuances of hearing ranges and the effects of age on auditory sensitivity.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants assert that a string vibrating at 20Hz will produce an audible sound, while a string vibrating at 19Hz may not be heard, depending on individual hearing ranges.
  • Others argue that human hearing is not strictly defined by the nominal range of 20Hz to 20kHz, noting that sensitivity varies significantly among individuals and can degrade with age.
  • A participant references a standard ear sensitivity curve to illustrate how hearing sensitivity decreases at lower frequencies, particularly below 1000Hz.
  • Some participants challenge the idea of a hard limit in hearing, suggesting that while sensitivity decreases, it does not mean that frequencies just below the threshold are completely inaudible.
  • There is mention of the perception of low frequencies, where at very low frequencies (e.g., 1Hz), individuals may perceive pulses rather than a continuous tone.

Areas of Agreement / Disagreement

Participants express disagreement regarding the interpretation of hearing thresholds and the implications of frequency ranges. While some believe in a clear distinction between audible and inaudible frequencies, others emphasize the gradual nature of hearing sensitivity and the lack of absolute limits.

Contextual Notes

The discussion highlights the variability in individual hearing capabilities and the complexity of auditory perception, particularly at the lower end of the frequency spectrum. Limitations in measuring sensitivity at extreme frequencies are acknowledged, but not resolved.

toesockshoe
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I know that the audible range is 20Hz to 20000 Hz... does this mean if give a string a vibration such that it has a frequency of 20Hz... it will cause a vibration in the air with a equal frequency and thus make it audible? Does this also mean that a string with 19 Hz will be inaudible?
 
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Human hearing range is nowhere near that sharply defined. Yes, a 20hz string vibration is what we hear as 20Hz. The starting point for degraded hearing at the upper and lower ends is NOMINALLY 20Hz to 20KHz but the actual degradation points vary by individual. As we get older, the upper end starting point in particular drops off. Some people for example will be born with an upper end starting to degrade at 18KHz and dropping off such that they don't hear anything above 20KHZ but when they are 95 the degradation might start at 15KHZ and drop to nothing at 16KHz. These are just made up examples, but you get the idea, I assume.
 
400px-Lindos1.svg.png
This is a standard ear sensitivity curve. See also https://en.wikipedia.org/wiki/Equal-loudness_contour.
 
phinds said:
Human hearing range is nowhere near that sharply defined. Yes, a 20hz string vibration is what we hear as 20Hz. The starting point for degraded hearing at the upper and lower ends is NOMINALLY 20Hz to 20KHz but the actual degradation points vary by individual. As we get older, the upper end starting point in particular drops off. Some people for example will be born with an upper end starting to degrade at 18KHz and dropping off such that they don't hear anything above 20KHZ but when they are 95 the degradation might start at 15KHZ and drop to nothing at 16KHz. These are just made up examples, but you get the idea, I assume.
Alright, but you get my point... if an individuals hearing range IS defined to be 20Hz to 20KHz... they he would be able to hear a 20Hz string but NOT a 19 Hz string right? (again... assuming that some arbitrary individuals hearing range is 20Hz to 20KHz).
 
toesockshoe said:
Alright, but you get my point... if an individuals hearing range IS defined to be 20Hz to 20KHz... they he would be able to hear a 20Hz string but NOT a 19 Hz string right? (again... assuming that some arbitrary individuals hearing range is 20Hz to 20KHz).
Sure, if things actually worked that way then yes that is they way thing would work but my point is they DON'T work that way. Nobody's hearing is such that they can hear one frequency perfectly and a small frequency different from that not at all and no "definition" you create is going to change that fact.
 
toesockshoe said:
Alright, but you get my point... if an individuals hearing range IS defined to be 20Hz to 20KHz... they he would be able to hear a 20Hz string but NOT a 19 Hz string right? (again... assuming that some arbitrary individuals hearing range is 20Hz to 20KHz).
Wrong. No such hard limit exists. If you look at the curve in post #3, you will see, that the ear is progressively less sensitive below 1000Hz, and the sensitivity decreases fast when you get to about 20Hz. The curves stop at 20Hz and 20kHz because outside these frequencies it is hard to get good aural measurements.
 
Svein said:
Wrong. No such hard limit exists. If you look at the curve in post #3, you will see, that the ear is progressively less sensitive below 1000Hz, and the sensitivity decreases fast when you get to about 20Hz. The curves stop at 20Hz and 20kHz because outside these frequencies it is hard to get good aural measurements.
alright got it.
 
phinds said:
Sure, if things actually worked that way then yes that is they way thing would work but my point is they DON'T work that way. Nobody's hearing is such that they can hear one frequency perfectly and a small frequency different from that not at all and no "definition" you create is going to change that fact.

understood!
 
toesockshoe said:
Does this also mean that a string with 19 Hz will be inaudible?

no, you hear ALL the way down as low as you care to go ... the difference is that from around 20 - 25 Hz and lower in frequency, you no longer hear a tone, rather you hear the individual pulses.
So at say 1Hz you hear a pulse once a second, at 0.1 Hz you hear a pulse once every 10 seconds

This is quite easy to experiment with a function generator that has a good low frequency range into a loudspeakerDave
 

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