Wednesday, February 23, 2011

Loudnessss !


Sound loudness is a subjective term describing the strength of the ear's perception of a sound. It is related to sound intensity, but can't be considered identical to intensity. Sound intensity is the power per unit area.

Environmental Noise
Weakest sound heard0dB
Whisper Quiet Library30dB
Normal conversation (3-5')60-70dB
Telephone dial tone80dB
City Traffic (inside car)85dB
Train whistle at 500', Truck Traffic90dB
Subway train at 200'95dB
Level at which sustained exposure may result in hearing loss90 - 95dB
Power mower at 3'107dB
Snowmobile, Motorcycle100dB
Power saw at 3'110dB
Sandblasting, Loud Rock Concert115dB
Pain begins125dB
Pneumatic riveter at 4'125dB
Even short term exposure can cause permanent damage - Loudest recommended exposure WITHhearing protection140dB
Jet engine at 100', Gun Blast140dB
Death of hearing tissue180dB
Loudest sound possible194dB

Long time exposer to these loud decibels can cause ear and brain damage. For example, 110 Decibels Regular exposure of more than 1 minute risks permanent hearing loss.


Frequency is the number of occurrences of a repeating event per unit time. Frequency f is the reciprocal of the time T taken to complete one cycle (the period). In wave motion, it is the number of waves that pass through a given point per second.

File:Sine waves different frequencies.svg

In this picture, the red is the lowest frequency because the waves are spread farther apart while the purple is the highest frequency because the waves are closer together. 


My Singing Voice -


Tuning Fork

1.) .0097 2.) .0127 3.) .0162 4.) .0191 5.) .0221 6.) .0257 7.) .0286
7 waves/.0189 per second = 370.4

Different animals hear different frequencies than humans. Elephants can hear lower frequencies, while dolphins can hear louder. The range they hear in is called infra sound, because infra means lower. They can hear lower than human hearing.

Tuesday, February 22, 2011

Sound Crossword

3. connection from signal source
4. Pressure Level (SPL) the loudness of an acoustic wave stated in dB that is proportional to the logarithm of its intensity.
6. a unit of electrical power
8. the length of a sound wave in air
9. number of occurrences of a repeated event per unit time
11. an electrical circuit designed to increase the current or voltage of an applied signal
13. a sensation perceived by sense of hearing
16. The relative magnitude of a signal
1. The quality of a sound related to its harmonic structure.
2. a loudspeaker designed to reproduce bass frequencies
5. the part of a dynamic loudspeaker attached to the voice coil that moves and produces the sound
7. (highs) the upper end of the audio spectrum reproduced by tweeters, usually 3 - 4 kHz and up
10. a complete path that allows electrical current from one terminal of a voltage source to the other terminal
12. a loudspeaker transducer designed to reproduce low-frequency sounds
14. (E) a unit of measurement used to measure how much "pressure" is used to force electricity through a circuit
15. The low end of the audio frequency spectrum between 0Hz to about 200 Hz