Decibels (dB)

Measures the volume or loudness of a sound - the higher the dB, the louder the sound

Named after scientist Alexander Graham Bell who researched hearing and speech

Examples of daily dBs

• Normal conversation: 60-70 dB

• Movie theater: 74-104 dB

• Motorcycles and dirt bikes: 80-110 dB

• Music through headphones at maximum volume, sporting events, and concerts: 94-110 dB

• Sirens: 110-129 dB

• Fireworks show: 140-160 dB

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Hertz (Hz)

Describes the pitch of a sound - how many vibrations per second

Lower the Hz, lower the pitch of the sound which make it difficult to hear

Named after physicist Heinrich Rudolf Hertz who researched electromagnetic waves

Examples of low Hz

• Human heartbeat, background noises, waves, severe weather, sounds from large animals, musical instruments like drum, bass instruments

• Common machines: Compressors, air-conditioning units, ventilation units, road vehicles particularly electric vehicles, aircraft,

• Heavy equipments: Industrial machinery, artillery, mining explosions, air movement machinery including wind turbines

Examples of high Hz

• Bird chirps, baby cries, screams. squeaks

• Computer and phone sounds, glass breaking, school bell

• Giraffes

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Normal hearing

• Hear sounds at or below 25 dB

• Detect sounds between 20 and 20,000 Hz

 

Loud sounds (dB) damage normal hearing

• Sounds above 90 dB for long periods of time can lead to hearing damage but is painless

• Sounds above 110 dB cause discomfort, in addition hearing damage

• Sounds above 130 dB becomes painful and causes instant hearing loss​

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Hearing loss makes it difficult to hear sounds of certain frequency (Hz)

• It is common to have problems to hear high-pitched sounds such as birdsong, children's voices

• With mild-moderate hearing loss,  there is difficulty with hearing higher Hz sounds (2,000 to 8,000 Hz), which includes consonants like "s," "f," and "th" in speech