Sound Levels

Introduction

As sound level meters I used two devices.

First device marked with "IP" in the below tables is iPod Touch 3rd Generation, which I used with the "Decibel" app by Gadget Frontier (Tomas Matuschek) with "Apple Earphones with Remote and Mic". Minimum reading I saw in quiet living room was 37 dB.

Second device is Nokia 5140i with "Sound meter" program. The Sound meter has three "Noise tuning" options: Off ("OFF"), A weighting ("A") and C weighting ("C"). Minimum reading I got in the same quiet living room was 50 dB.

Comment: with my Android phone I found "Noise Meter" (by JINASYS), which I might try some day with my computer-related sound measurements (quiet living room 31.8 dB).

About Measurements and Weighting

Because of the quite high minimum levels I needed to locate the sound meters close to the noise sources to get some kind of readings. I also needed to put the laptops in high burden to get measurements I could compare with each other. I didn't put the sound meters in front of the air flow, because that would distort the readings.

What is weighting? Quote from Wikipedia (April 2012): "A-weighting is the most commonly used of a family of curves defined in the International standard IEC 61672:2003 and various national standards relating to the measurement of sound pressure level." According to the graph on the same page, C-weighting seems to weight lower frequencies from 10 Hz to 1000 Hz.

Hearing Range and Some Sound Levels from the Web

Hearing range or audible frequency is approximately from 20 Hz to 20 kHz.

- 30 dB whisper (1.8 m)

- 40 dB raindrops

- 40 dB quiet living room

- 60 dB conversation (1-2 m)

- 80 dB telephone dial tone

- 85 dB busy city traffic

- 90 dB hair dryer

- 90 dB heavy truck

- 105 dB rock concert

Some Subjective Stuff

HP laptop is way too loud. FS laptop CPU fan noise is annoying, because it turns on and off instead of keeping a steady flow especially when the laptop is plugged in as there is no reason to conserve battery power.

Mac Pro isn't very loud, but it can affect my concentration also. Wings desktop is too loud even though I assembled it to be quiet, so I have stuff there to learn.

The plastic Logitech keyboard is noisier than the plastic and aluminum Apple Keyboard.

FS Laptop

Measuring location: left, near CPU fan. High CPU burden.

HP Laptop

Measuring location: back, near CPU fan. High CPU burden.

Keyboard: Apple Keyboard with Numeric Keypad

Measuring location: above, while typing. Computer off.

Keyboard: Logitech Keyboard K120

Measuring location: above, while typing. Computer off.

Mac Pro

Measuring location: in front of intake, low CPU burden. With the A-weighting setting Nokia couldn't get a reading.

Wings Desktop

Measuring location: top, above the Antec P183 case hole that is near the TriCool Top Fan, which was not functioning, so I could measure the computer fan sounds through a hole without getting my meters in front of air flow. I used the TriCool Rear Fan in three positions: 0 ("Off"), 1 ("Middle") and 2 ("Full"). Of course the mother board, CPU and PSU fans were working also.

Last modified: April 26th, 2012

Author: Tomi Häsä (tomi.hasa@gmail.com)

URL: http://sites.google.com/site/tomihasa/sound-levels