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Thread: 100dB waves?

  1. #1
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    Default 100dB waves?

    During my recent vacation at a beach resort, I spent my time listening to the sound of waves and to see how well Harbeth sounds compared to the natural sound.

    What interested me was the waves could be heard as far as 300 to 400 meters even with the air conditioner's compressor running just about 1 meter above my head. That prompted me to search the google (where else?) and found that the sound of waves breaking in to the beach is more than 100dB loud!!

    But I did not go deaf nor the guy who manages the water scooter who has been there for years did not show any hearing deficiency. At least not to my crude observation.

    Isn't it interesting to listen to nature's sound even it is extremely loud we just don't get fatigue nor annoyed with it? And do you really suffer hearing impairment above 85dB after few hours.

    ST

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    Default Loud noise kills ears!

    Quote Originally Posted by STHLS5 View Post
    During my recent vacation at a beach resort, I spent my time listening to the sound of waves a ... what interested me was the waves could be heard as far as 300 to 400 meters even ... the sound of waves breaking in to the beach is more than 100dB loud! Isn't it interesting to listen to nature's sound even it is extremely loud we just don't get fatigue nor annoyed with it? And do you really suffer hearing impairment above 85dB after few hours.
    You have touched on a number of issues.

    First, yes, there is no doubt that if you expose yourself to loud sounds, all the evidence is that you do destroy your hearing. Whether that destruction occurs over years and decades or after one night at the rock concert* depends on many factors. So please, do not think that you can get away with exposure because you can't! Your ears, like a car odometer, clock-up evidence the lifetime of use and abuse. And those in the WHO who have studied loudness exposure lay-down a recommendation that long term exposure should be limited to 85dB to preserve hearing. But that does not means 85dB is safe.

    The other factor experts report on is the spectral content of the loud sound. If, as you have observed, the spectrum is like hiss (actually wave sound will be more like pink noise than white noise hiss) with most of the energy in the low frequencies and progressively less in the highs, then the ear is better protected. The fast way to destroy your hearing is to work in a factory on a repetitive job which has the combination of loud, high pressure steam (white noise, lots of high frequency energy), hammering of metal on metal (impuslive sound, lots of HF energy) and a drone or whistle from some machinery. Analysis of such damaged ears show a generally low sensitivity to normal sound plus a hole in the frequency response where the whistle has literally killed the sensory hairs at that physical place along the organ of hearing. I myself have a small notch in my right ear's response which appeared between hearing tests a few years ago followed by a quick recovery to normal beyond that. How it occurred and why it occurred is a mystery as I have always been extremely careful about loud sounds around me. But it's there, and it has no sinister cause and is sufficiently high-up the scale that it has no effect on listening. So be careful!

    *As I mentioned previously, the audiologist told me that his previous patient was a 17 year old girl who had been in the front row of a pop concert next to the PA speakers. That one evening's exposure had completely destroyed her hearing. She had zero hearing acuity, hence there was nothing he could do for her. She will spend the rest of here life as profoundly deaf.

    P.S. I can make a very convincing surf sound by taking a computer generated pink noise signal and modulating it with a slow-moving wave to give it the ebb and flow effect. I could have saved you the bother of taking a vacation altogether!
    Alan A. Shaw
    Designer, owner
    Harbeth Audio UK

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    Default Exposure and loudness

    Quote Originally Posted by A.S. View Post
    ..(actually wave sound will be more like pink noise than white noise hiss)
    I believe the wave sound frequencies is from 30Hz to 10kHz. The reason why the loudness of waves interested me was it gave a sense of pleasure even compared to classical music after prolonged exposure.

    Meanwhile, there are a number of things that I am concerned with. First, life at the seaside is common in human civilization. It is hard to believe that the beautiful sound of waves will destroy our hearing. I can't imagine one day to see notice board at the beach carrying a warning sign " The sound of waves may damage your ears". :)

    Second, research on hearing losses related to exposure to loud noise talks about continuous exposure. About 1 or 2 hours at 85dB and few minutes around 100dB. However, waves are cycles. You will have at least a few second gaps between two noise peaks. This may be indirectly helps to protect our ears.

    Quote Originally Posted by A.S. View Post
    As I mentioned previously, the audiologist told me that his previous patient was a 17 year old girl who had been in the front row of a pop concert next to the PA speakers. That one evening's exposure had completely destroyed her hearing
    My friend who worked for EMI is suffering from hearing loss after one live audition of local rock band in the studio. He is suffering from a constant ringing in his ears, which started immediately after the band stopped playing.

    ST

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    Default Absolute silence and noises inside your head

    It is a noisy world out there. I just got my first 31dB rated ear plug. After the initial discomfort I am getting used to it. I can't hear the mouse clicks and hate the stomping in the head when I walk. Plus the orange coloured stuff sticking out my ears making people laugh behind my back. It is okay- I can't hear them. :-)

    _____
    Have you experienced absolute silence? In my experience with the ear plugs or when I sit silently in my room the noisier it becomes. You can sit still and hear your heart beat but eventually as time goes by there seemed to be some sort of high pitch noise inside your head. The kind you experience in a deep jungle. It may be the symptom of tinnitus. However, this is not unique to me as even younger persons in my family do experience that the quieter it is the noisier it becomes inside their head after the initial silence. It stops the moment there is another noise no matter how soft it is.

    Anyone experienced this?

    ST

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    Default Sounds in your head - otoacoustic emissions

    Quote Originally Posted by STHLS5 View Post
    Have you experienced absolute silence? In my experience with the ear plugs or when I sit silently in my room the noisier it becomes. You can sit still and hear your heart beat but eventually as time goes by there seemed to be some sort of high pitch noise inside your head...
    Yes, I am familiar with that. I work at the R&D Centre, deep in the woods alone and in silence. As I type this now the loudest sounds I can hear is a gentle whir from the PC fan and that's all. I'll measure the noise level later with a sound level meter.

    If I concentrate I also can hear whistles in my head, especially in bed before dropping off. Their loudness and their frequency make-up (spectra) seem to vary somewhat depending on stress level etc.. Sometimes it is more of a sawtooth buzz with multiple frequency components, sometimes a more pure tone. I believe that it is normal and masked by everyday noise.

    Did you know that the ear actually generates noises and tones? These otoacoustic emissions are completely normal and can be used to indicate the health of normal ears. They are also being studied for use as a fingerprint to the individual and are being considered for positive security identification, which implies that they are sufficiently unique and permanent in character.

    From the above PDF link:

    Otoacoustic emissions are small sounds caused by motion of the eardrum in response to vibrations from deep within the cochlea. The healthy cochlea creates internal vibrations whenever it processes sound.
    Impaired cochleae usually do not. Some healthy ears even produce sound spontaneously as internal sounds are processed and amplified. As described later, the cochlea's capacity to generate sound is intimately associated with its achievement of normal auditory threshold, and the underlying mechanism is very easily damaged. To record the sounds made by the cochlea an earphone and microphone combination probe is fitted into the ear canal. The middle ear has to be working efficiently in order to conduct the minute cochlear vibrations back to the ear drum - acting like a stethoscope. A good fitting of the probe is important. Closure of the ear canal by the probe greatly increases the sound pressure created by any ear drum vibration. It also excludes unwanted external sounds. Normally the ear to be tested is given mild acoustic stimulation to evoke an otoacoustic emission. Clicks, tones, noise and even speech all elicit an OAE response. There is a unique OAE response to every stimulus. Depending on the nature of the sound presented, different signal processing techniques are effective in extracting the OAE from the stimulus and other noises ... The essential fact about OAEs is that their presence is always good news about cochlea and middle ear function. It usually means hearing is within normal limits around the stimulus frequency evoking the response - but this is not guaranteed. There can be problems further along the auditory pathway and there is much still to learn about OAEs and cochlear physiology. In the following pages we look at the use of OAEs today for newborn screening and for clinical investigation, and at the auditory physiology and biophysics behind OAEs and OAE technology.
    As mentioned, the hearing acuity of even a baby can be explored by stimulating the ear and listening (measuring) to the ear's output response to the stimulus. This allows even babies hearing to be tested, they of course being incapable of communicating to the tester what they can hear.
    Alan A. Shaw
    Designer, owner
    Harbeth Audio UK

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    Default Wonders of our creator

    Almost everyday, I look for new discoveries about hearing but otoacoustic emissions is something new and amazing for me. Thanks Alan.

    I am always aware of noises inside my head under very quiet environment but rarely discuss them with anyone for fear of being ridiculed. Thanks to you, now I can go back and enjoy my music with more respect to the wonders of our creator.

    ST

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    Default Hands up and admit you don't understand!

    Quote Originally Posted by STHLS5 View Post
    ... but rarely discuss them with anyone for fear of being ridiculed...
    You should never fear ridicule if your quest is for more enlightenment and less dogma. Personally, I have no problem being the awkward one at the back of the class putting my hand up and saying 'I don't understand that - would you mind simplifying it for me?'. What matters is getting to the heart of the idea and to carry it in your own head as a necessarily simplistic but tolerably robust theory. Providing that we recognise it as work in progress, likely to be at least partially wrong but keep an open mind to adapting and honing it, then in the longer term, knowledge grows. And with knowledge, self-esteem and well being.

    We, in common with our ancestors back to the stone age, believe that we are at the very apex of technological development. In fact, we are living in our descendent's dark ages. There are so many aspects even of our own bodies and minds that are barely understood, let alone technological matters. We can truly consider ourselves sophisticated when the all-pervasive influence of our hormones in regulating our entire lives is widely discussed and thoroughly understood. Until then society will remain dysfunctional and the prisons full.
    Alan A. Shaw
    Designer, owner
    Harbeth Audio UK

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    Default My working noise level

    OK, you prompted me to measure the background noise in my work room here in the countryside. According to my B&K sound level meter it measures about 35dBA. Attached scale shows that here the ambient noise level is off the bottom of the scale.

    BTW, I can't find a noise chart scaled in the more familiar dBA, so this will have to suffice in Phons. As I understand it, there is no direct conversion between dB and Phons except at a reference level so let's ignore that and just concentrate on the issue that is, I work in virtual silence.

    I do wonder though if this is an unusually quiet environment for a speaker designer which can only be a good thing. STHLS5 mentioned that he was aware of noises within his head. If I were to play music even at a very moderate level (say, 80dB) here, my ears would frequently pop as the muscles controlling the ear drum tighten and relax tracing the loudness of the music up and down. Are you familiar with that sensation? It must be a basic protective mechanism relating to the ear's Automatic Gain Control (AGC) and tensioning the ear drum when a louder sound is detected than the preceding average.
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    Alan A. Shaw
    Designer, owner
    Harbeth Audio UK

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    Default Ear's Automatic Gain Control (AGC)

    Quote Originally Posted by A.S. View Post
    OK, you prompted me to measure the background noise in my work room here in the countryside. According to my B&K sound level meter it measures about 35dBA. .....

    BTW, I can't find a noise chart scaled in the more familiar dBA......

    ...STHLS5 mentioned that he was aware of noises within his head. If I were to play music even at a very moderate level (say, 80dB) here, my ears would frequently pop as the muscles controlling the ear drum tighten and relax tracing the loudness of the music up and down. Are you familiar with that sensation? It must be a basic protective mechanism relating to the ear's Automatic Gain Control (AGC) and tensioning the ear drum when a louder sound is detected than the preceding average.

    Let me clarify. I hear noises whenever there is absolute silence (but, after reading about otoacoustic, maybe, there is no such thing as absolute silence). Let me not be accused of hearing noises (and voices) at all time!

    I listen music in virtual silence. Measurement using A-Weighting filter gave me no reading. My SPL meter's lowest possible measurement is 32dB. However, using C-Weighting filter it gave me an average of 36.5dB.

    Yes, I am very much aware of something similar to that. Some sort of blockage that feels like clearing when you swallow a little water or saliva. It is more prominent in my right ear which is also more sensitive to loud noises or when the music is not to my taste where I will develop a slight pain sensation at the back of the right ear (maybe the muscles around my ears, anyway that's what the doctor told since I can't tell exactly where I feel the pain but definitely not in my ear). Are we referring to the same thing?

    The other thing I noticed when using ear plugs is on removing them after an extended period ,my voice sounded so clear and "pristine" for a short while. This shows how much noise pollution has hampered our hearing senses.

    I have attached loudness comparison chart extracted from www.sengpielaudio.com .

    ST

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    Default SPL readings

    Quote Originally Posted by STHLS5 View Post
    .... Measurement using A-Weighting filter gave me no reading. My SPL meter's lowest possible measurement is 32dB. However, using C-Weighting filter it gave me an average of 36.5dB...
    I re-measured my room due to the increase in the air conditioner's noise level. Now it reads 32dB in A-Weighting setting and close to 42dB in C-Weighting. The only possible frequency to give a 10dB difference between A and C weighting is at 200Hz. Could the air cond noise be at 200Hz?

    ST

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