Ask An Engineer - How loud are kids?

With working from home arrangements well underway, it's not uncommon for parents to be interrupted by the shouting, hollering and the general hullabaloo of kids with pent up energy. But how loud are kids? We passed that question on to Acoustics/Noise Specialist Lindsay Leitch. Here's her response:

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In this new era of working from home with kids in tow, it may already be painfully obvious that children can be pretty noisy. But how loud are they?

Firstly, we need to consider what constitutes a sound. A sound is created by something that vibrates, such as an engine, or a musical instrument, these vibrations travel through the air as a pressure wave - like ripples in a pond. When your ears detect these pressure variations, they are converted into electrical impulses that are transmitted to your brain and interpreted as sounds. An amazing amount of information can be transmitted through variations in frequency (how high or low a sound is), loudness, duration and a lot of more subtle factors such as for speech and whether it is pleasurable or annoying.

So how do you measure sounds? A microphone works roughly in the same way as your ears. The diaphragm of the microphone picks up the pressure variations and converts them to electrical signals. If the microphone is connected to a sound level meter, these sounds can be measured in units of pressure (Pascals - Pa) then converted to decibels (dB, a logarithmic scale).

The acoustics team in Christchurch and Auckland took a few sound level measurements in and around their homes offices of typical sounds using a phone app.

Activity

Sound pressure level, dB

Family eating lunch and conversation (small table so at 1m)

57 dB, 2 min

Mother telling off child at 3m

61 dB, 6 seconds

Standing while watching the kettle boil

66 dB

Son playing Xbox with headphones on

51 dB

Outside feeding the chicken

56 dB

On the patio

45 dB

In my office

 

34 dB with window closed

41 dB with window open

45 dB with music on

In the lounge with the window open where I’m working and my partner is doing crochet

39 dB

Partner talking at 2m

41 dB

Boiling the jug (highly reverberant room)

65 dB

At desk working

42 dB

Outside house, port in distance, no traffic

45 dB

Kids playing swingball

66 dB

Children yelling at each other (1m)

80 dB

And finally, to answer the original question – how loud are my children? I gave my two boys the challenge of seeing how high they could get the sound level to measure on my phone app. The result? 95 dB. Ouch. If you had that level of sound all day you would quickly go deaf!

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