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Sound Card Performance Technical Benchmarks

TechTalk

Ear Damage

Ear damage results when the ear is subjected to too loud of a sound, at the wrong frequency, for too long of a time, on too many occasions.

The following chart portrays the duration, in minutes per day, of sound level that can be sustained while causing acceptable levels of damage. The left hand axis is for noise in one octave bands, and the right axis is for noise in one-third octave bands.

For example, a noise signal, one-third octave wide, centered at 3 kHz, and having an intensity of 115 dB, can be listened to for only 1.5 minutes per day before permanent damage occurs.

One general trend is that ear damage occurs at the lowest sound levels at 3 kHz, but the ear is less susceptable to damage from the same noise of the same intensity, at higher and lower frequencies.

Another general trend is that reducing the noise level by about 10 dB, approximately doubles the length of time it can be tolerated without ear damage.

 

Illustration taken from The Encyclopedia of Science and Technology: "Acoustic Noise," McGraw Hill, Vol. 1, p. 80, 1997

Osha Standards

OSHA (U.S. Federal Safety Stanards) Are based on broadband noise. For every 5 dB increase in volume, the maximum exposure time per day is cut in half. Many think that OSHA standards permit sound levels that are too high.

OSHA Standards For Broadband Noise (A Weighted)
Maximum Level dB	Maximum Exposure Time, Hours
90	8
95	4
100	2
105	1
110	30 Minutes
115	15 Minutes

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