The Lombard Effect

by Arjun Jain

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A few weeks ago, I had an ear infection due to which I could not hear properly through my left ear. Apart from the  general discomfort, I observed something totally unexpected- I started speaking more softly, that is at a lower volume. Although I couldn’t notice this change myself, I was told of it by my friends and family.

Remembering the well known fact that people start talking very loudly when hearing loud music through headphones, I knew for sure that there had to be some relation.

So, I contacted some professors of Auditory cognition in hopes of finding out more. Josh Mcdermott from MIT suggested I look into the Lombard Effect.

-From Wikipedia:

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The Lombard effect or Lombard reflex is the involuntary tendency of speakers to increase their vocal effort when speaking in loud noise to enhance the audibility of their voice. This change includes not only loudness but also other acoustic features such as pitch, rate, and duration of sound syllables. This compensation effect results in an increase in the auditory signal-to-noise ratio of the speaker’s spoken words.

The effect links to the needs of effective communication as there is a reduced effect when words are repeated or lists are read where communication intelligibility is not important. Since the effect is also involuntary it is used as a means to detect malingering in those simulating hearing loss. Research upon birds and monkeys finds that the effect also occurs in the vocalizations of nonhuman animals.

The effect was discovered in 1909 by Étienne Lombard, a French otolaryngologist.

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So my speaking softer than before, was kind of an inverse Lombard Effect.

I searched for otolaryngologists on the web and contacted Mario A. Svirsky from the NYU Langone Medical Center, who clarified and explained many of my doubts regarding this.

Regarding the observation with my infected ear, the obstruction in my middle ear attenuated the air conducted signal but not the bone conducted one that much. This made my own speech appear louder, leading  me to decrease its amplitude to compensate.  To others, this sounded like just my speech becoming softer.

If you are not aware of air and bone conduction: sound can reach the inner ear by way of two separate paths, and those paths in turn affect what we perceive. Air-conducted sound is transmitted from the surrounding environment through the external auditory canal, eardrum and middle ear to the cochlea, the fluid-filled spiral in the inner ear. Bone-conducted sound reaches the cochlea directly through the tissues of the head.

I then asked whether deaf people could hear their own voices, as bone conduction could still be there. This depends on the type of deafness. Sensorineural hearing loss affect both air and bone conducted signals while conductive hearing loss affects air conducted signals more.

Another question was that when singers cup their ears sometimes, they are eliminating the air conducted part of the sound. Why do they do that? When they cover their ears, it emphasizes the bone conducted signal, so the singer can hear himself better even if other instruments are very loud.

Also, the skull conducts lower frequencies better than air. This is why people perceive their own voices to be lower and fuller than others do, and a recording of one’s own voice frequently sounds higher than one expects it to sound.

-From an article in Scientific American, Why does my voice sound so different when it is recorded and played back?,

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The voice you hear when you speak is the combination of sound carried along both paths. When you listen to a recording of yourself speaking, the bone-conducted pathway that you consider part of your “normal” voice is eliminated, and you hear only the air-conducted component in unfamiliar isolation. You can experience the reverse effect by putting in earplugs so you hear only bone-conducted vibrations.

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