Project description

LISTEN stands for Liaison In Scientific Training for European auditory Neuroscience. The LISTEN training network consists of leading European auditory neuroscientists working with several European companies to improve hearing aids (including cochlear implants) and pharmacological treatments for tinnitus and hearing loss.


Hearing is unique among the senses in its precision and speed. Behaviourally relevant sounds, which often rapidly fluctuate in intensity (volume), are tirelessly encoded by specialized synapses of the auditory pathway with sub-millisecond precision and high transmission rates. This phenomenal "neural machine" requires precise molecular components, cellular networks and still-to-be discovered mechanisms to process this information.

Hearing loss is a rapidly expanding health concern; it is the most prevalent disability- or disease-related condition in the world, with >100 Million Europeans affected(i). Hearing loss has a devastating social impact, reducing our ability to have a conversation in noisy environments, and consigning the deaf to social isolation. This negative impact is increasing and is projected to be in the top ten causes of disease burden in Europe by 2030(ii). In deaf patients, electrical stimulation by cochlear implants can be used with great success for sound encoding. However, man-made prosthetic devices cannot yet restore prominent features of our ears and central auditory system, such as the exquisite frequency selectivity and broad dynamic range required to recognise a voice or appreciate music, because neither the physiological mechanisms nor the disease-related changes are sufficiently understood.

Hearing loss can have other debilitating consequences, as sufferers begin to hear phantom sounds; these are loud, distracting and imaginary sounds, known as tinnitus. Tinnitus is also a major health problem in Europe, with around 30% of Europeans experiencing tinnitus at some point in their life; its prevalence is ~5% (~35 million inhabitants), and persistent tinnitus adversely affects quality of life in ~1% of the population(iii). Although tinnitus is typically preceded by hearing loss, it is usually not generated in the ear, but is 'created' by the brain. The general consensus is that tinnitus results from abnormal excitability in the central auditory system(iv). Hearing loss is a form of sensory deprivation and the affected parts of the brain then produce 'phantom sounds', analogous to an amputee still feeling excruciating pain in the hand of their severed arm. At the cellular level this is thought to occur via a form of homeostatic plasticity, in which neurons regulate their excitability and the strength of their inputs in order to compensate for the lack of sensory inputs. However, neither the location of the problem nor the exact plasticity processes that generate this aberrant activity are understood. Consequently, there are few tinnitus treatments beyond management of symptoms(v); hence this represents a major unmet need in European society.

Insufficient training of hearing scientists to remedy these ailments poses serious challenges in this era of increasing specialization. The main challenge is the interdisciplinary character of skills and knowledge needed. Hearing impairment generally involves multiple stages of auditory processing, requiring studies employing a bewildering variety of techniques. Understanding the auditory information highway with its high speed, extreme precision and broad dynamic range is critical for comprehending, diagnosing and finally treating hearing impairment. For example, poor speech perception in noisy environments is a prominent complaint of the hearing impaired. It does not correlate well with traditional estimates of inner-ear function like pure-tone threshold measurements, because both the task and the pathology can be very complex: the encoding of many simultaneous sound features (frequency, intensity, temporal structure, and their mutual monaural and binaural interactions) can be disturbed at multiple levels. Improved strategies for artificial sound encoding by auditory prostheses (traditional hearing aids, cochlear and auditory brainstem implants) will greatly benefit both from insight into normal physiological sound processing and from knowledge on the consequences of the loss of synapses or neurons in any part of this circuit caused by genetic defects or noise-induced or ototoxic damage.

Hearing loss and tinnitus are large medical problems that require a multidisciplinary approach aimed at understanding the underlying mechanisms. In LISTEN, multiple laboratories with specialist skills form a collaborative network to train 10 ESRs to tackle complex questions about sound perception, listening and hearing, and particularly the alterations in perception in subjects suffering from hearing loss and tinnitus.


(i) source: Global Burden of Disease, 2004,WHO
(ii) Mathers and Loncar (2006) PLoS Medicine 3: e442
(iii) Holmes and Padgham (2009) J Clin Nurs 18: 2927-37
(iv) Langguth et al (2013) Lancet Neurol 12:920-30; Auerbach et al (2014) Front Neurol 5: 206
(v) Baguley et al (2013) Lancet 382: 1600-7