Pure Word Deafness
Pure word deafness is a specific inability to understand spoken words despite hearing them perfectly well as sounds. The person can hear that someone is speaking, and can hear other environmental sounds normally, but the spoken words themselves fail to be understood as language.
This has traditionally been attributed to a lesion in the dominant temporal lobe, and is considered a relatively 'pure' disorder in the sense that hearing itself, along with reading and writing, are typically preserved, isolating the deficit specifically to the recognition of spoken language.
Recognition features
- Normal hearing for non-verbal sounds and awareness that speech is occurring
- Spoken words are not understood, despite being heard
- Reading and writing are typically preserved, since the deficit is specific to spoken language
- Usually associated with a lesion in the dominant temporal lobe
Eliciting it at interview
- Test hearing for non-verbal sounds separately from comprehension of spoken words to confirm hearing itself is intact
- Compare spoken comprehension against reading comprehension, since a marked discrepancy favouring reading over listening supports this specific diagnosis
- Arrange formal audiological assessment where there is any doubt about whether reduced comprehension reflects a genuine hearing deficit
Distinguishing features
- Differs from ordinary deafness in that hearing for non-verbal sounds is preserved; only the understanding of spoken words is affected
- Differs from agnostic alexia and visual asymbolia in affecting spoken rather than written language
- Reading and writing are usually preserved, distinguishing this from receptive aphasias that also affect written language
Common misconceptions
- That pure word deafness is a hearing problem; formal hearing tests are typically normal, and the deficit lies specifically in recognising spoken language as meaningful
- That the person cannot communicate at all; written communication typically remains fully available and should be used
Related phenomena
Receptive Aphasia · Agnostic Alexia
Practice this
A patient can hear that people are speaking and recognises other environmental sounds normally, but cannot understand a single spoken word said to him, though his reading and writing remain completely unaffected. What is this? · A patient cannot recognise or read aloud any written words placed in front of him, though he can copy the same words by hand, and he understands everything said to him without any difficulty. Before revealing the answer: is this pure word deafness? · A patient shows a specific pattern of language-comprehension disturbance. Before revealing the answer, decide what distinguishes agnostic alexia from pure word deafness. · A patient shows a specific pattern of language comprehension disturbance. Before revealing the answer, decide what distinguishes pure word deafness from visual asymbolia. · You suspect pure word deafness in a patient. Before revealing the answer, decide how you would assess for this. · Explain why pure word deafness is usually associated with a lesion in the dominant temporal lobe specifically.
Illustration
A 58-year-old woman following a left temporal lobe injury can clearly hear when the television is on and reacts normally to a sudden loud noise, but is unable to understand a single word spoken directly to her, though she can read the same sentence written on a card and respond to it appropriately without difficulty.
References
- Casey, P. & Kelly, B. (2019). Fish's Clinical Psychopathology, 4th ed. Ch. 4, 'Disorders of Thought and Speech'.