The CherISH network

We combine advanced medicine, evidence based psychology with inovative engineering

Cochlear implants

Cochlear implants replace the function of damaged sensory hair cells inside the inner ear.

Unlike hearing aids, which mostly amplify sounds, cochlear implants bypass most of the peripheral auditory system and convert recorded sounds into electrical signals stimulating directly the auditory nerve.

Several systems are available but generally they have:

  • A microphone to pick up the sound from the environment;
  • A speech processor to decompose the sound into frequency bands, select and arrange sound components and forward it to a transmitter placed on the head surface;
  • A receiver, implanted under the skin, converts the sound into electric impulses
  • A stimulation electrode directly stimulates the auditoru nerve, bypassing acoustic signal transduction of the inner ear.

Watch this brief video that illustrates how a cochlear implant functions

Courtesy of Dr. Lorenrenzo Picinali, AUDIO EXPERIENCE DESIGN, Imperial College London, UK

What is?

Artificial intelligence (AI): refers to the development of computer systems that can perform tasks that typically require human intelligence. 

Deep neural network (DNN): is a specific type of machine learning that aim to mimic the information processing of the brain.

Electroencephalography (EEG): is a medical diagnostic tool used  to measure the electric activity in the brain (brain activity).

Sound localisation (SL): is the ability to determine the location of a sound source in space.

Interaural time difference (ITD): is the time delay between a sound wave reaching one or the other ear. The delay is zero for a sound in front or behind the head. A sound wave on the right will first reach the right ear and thereafter the left ear.

Interaural level difference (ILD): is the difference in loudness between the two ears.

Machine learning (ML): is a subset of AI where systems learn and improve by experience without being explicitly programmed.

Spatial Hearing (SH)

Spatial hearing is our ability to understand where sounds are coming from by using both ears. This includes figuring out the direction of a sound and distinguishing it from background noise. We rely on comparing the signals received by each ear, noticing differences in time and loudness between them. This helps us locate the source of a sound, filter out unwanted noise, and focus our attention on specific sounds. Essentially, spatial hearing allows us to perceive the location, characteristics of sounds in our environment and to differentiate different sources of acoustic information.

What happens if you lose spatial hearing?

Losing spatial hearing would make it difficult to perceive and navigate the environment, posing safety risks, communication challenges, and orientation difficulties. It could also diminish the immersive quality of sensory experiences and make it hard to filter out background noise in daily activities.

What is the "cocktail effect party"?

Imagine you’re at a crowded party with lots of people talking, music playing, and other background noise. Despite the cacophony, you are able to focus on and understand the words of the person you’re talking to.

The “cocktail party effect” is your brain’s ability to pick out and comprehend that specific conversation while ignoring the surrounding chatter and noise. It’s like tuning in to one channel while disregarding the others.

What animal is known for having exceptional spatial hearing ?

Owls are often cited as having exceptional spatial hearing. Their unique facial structure, with asymmetrical ears and a dish-shaped face, allows them to locate prey with remarkable accuracy. The asymmetry in their ear placement enables them to detect minute differences in the time it takes for a sound to reach each ear, helping them pinpoint the source of the sound.