Many of us have just spent the Christmas season with a persistent and irritating ringing noise in our ears. But now that the relatives have gone home for the year, it’s worth remembering that a large proportion of the population suffers from a more persistent ringing sensation – tinnitus. It happens in the absence of noise, it’s one of the most common symptoms of hearing disorders, and it’s loud enough to affect the quality of life of around 1-3% of the population.
There have been many suggested treatments but none of them have become firmly established and most simply try to help people manage or cope with their symptom. Now, Hidehiko Okamoto from Westfalian Wilhelms University has developed a simple, cheap and enjoyable way of reducing the severity of the ringing sound. The treatment has showed some promise in early trials and even better, it is personally tailored to individual patients.
The method is simple. Find out the main frequency of the ringing sound that the patient hears – this becomes the target. Ask the patient to select their favourite piece of music and digitally cut out the frequencies one octave on either side of this target. Get the patient to listen to this “notched” piece of music every day. Lather, rinse and repeat for a year.
Okamoto tried this technique in a small double-blind trial of 23 people, eight of whom were randomly selected to receive the right treatment. Another eight listened to a piece of music that had a random set of frequencies cut out of it, while seven were just monitored. The treatment seemed to work. After a year, the treatment group felt that their ringing sensation was around 30% quieter, while the other two groups showed no improvements.
We’re used to thinking of neglect as a lack of appropriate care, but to a neuroscientist, it has a very different meaning. “Spatial neglect” is a neurological condition caused by damage to one half of the brain (usually the right), where patients find it difficult to pay attention to one half of their visual space (usually the left).
This bias can affect their mental images too. If neglect patients are asked to draw clocks, many only include the numbers from 12 to 6, while some shunt all the numbers to the right side. When two famous neglect patients were asked to describe a familiar square in Milan, the city they grew up in, the landmarks they reported shifted depending on where they pictured themselves standing in the square. They would only report buildings to the right of their imagined position – swap the location and new buildings would suddenly come into mental view.
Patients tend to be particularly unaware of things on the left if other objects on the right are vying for their attention – this phenomenon, where only one of two simultaneously presented objects is seen, is called “visual extinction“.
Neglect is clearly a fascinating condition but also a debilitating and underappreciated one. It affects up to 60% of patients who suffer strokes on the right side of their brain, and it can hamper recovery and deny patients their independence. As such, there are plenty of researchers interested in finding ways of improving its symptoms. David Soto from Imperial College London is one of them, and he has discovered a deceptively simple way of helping neglect patients to regain their lost awareness – listen to their favourite music.
Soto was encouraged by a recent study, which found that stroke victims showed greater improvements in both memory and attention when they tuned into music than when they listened to audiobooks or worked in silence. And other studies have suggested that emotional faces are less likely to fall prey to visual extinction than less compelling images. But Soto wanted to see if the patient’s own emotional state had anything to do with their awareness. Would it be possible to reduce the symptoms of neglect simply by making patients feel happier through the medium of pleasant melodies?
Have you ever looked at a piano keyboard and wondered why the notes of an octave were divided up into seven white keys and five black ones? After all, the sounds that lie between one C and another form a continuous range of frequencies. And yet, throughout history and across different cultures, we have consistently divided them into these set of twelve semi-tones.
Now, Deborah Ross and colleagues from DukeUniversity have found the answer. These musical intervals actually reflect the sounds of our own speech, and are hidden in the vowels we use. Musical scales just sound right because they match the frequency ratios that our brains are primed to detect.
When you talk, your larynx produces sound waves which resonate through your throats. The rest of your vocal tract -your lips, tongue, mouth and more – act as a living, flexible organ pipe, that shifts in shape to change the characteristics of these waves.
What eventually escapes from our mouths is a combination of sound waves travelling at different frequencies, some louder than others. The loudest frequencies are called formants, and different vowels have different ‘formant signature’. Our brains use these to distinguish between different vowel sounds.