Olfactory-auditory synesthesia

Alternative names could be smell-to-sound or smell-to-musical note synesthesia

Olfactory-auditory synesthesia is a very uncommon type, despite often being cited as an example of synesthesia in general articles in magazines and websites, which frequently begin with statements affirming that synesthetes can “taste colours and hear smells” when in actual fact it is almost impossible to find anyone with these types of synesthesia. In Sean Day's study on the prevalence of the different types, less than 0.5% of synesthetes reported this type of experience.

Olfactory-auditory synesthesia consists of hearing sounds in response to different smells. They can be either general or musical sounds: tones, frequencies, chords, hums or whistles, for example. A complex smell can produce a mix of two or more sounds, which might even create a melody. Some of these people hear the sounds physically as if they were real, while others simply have a strong impression of a sound or tone, consciously perceived with each particular smell. The auditory impressions are automatic and involuntary, different for each synesthete and basically consistent – the same smell always evokes the same sound – although like all olfactory synesthesias they are somewhat “fragile” and can depend on the strength or novelty of the smell in question, the person’s olfactory capacity at any given time (our sense of smell has “good days and bad days” as it were), focus, relaxation, stress, emotion and mood.

Here are some descriptions written by people with this type of synesthesia:

“My daughter (aged 11) has smell -> sound. She's very musical and has perfect pitch so everything she smells corresponds to a certain musical note. A piece of broccoli may, for example, be a slightly sharp G flat in her mind (she's obviously tuned to A being 440 Hz so not every scent is 'in tune'). She also smells chords, so when she smells a perfume the three 'notes' of the scent all correspond to different musical notes. Interestingly, most of the time, the notes form for her a nice sounding consonant chord. She'll quite often smell more than one note in wine and beer too.”

(Source: This comment on the Synesthesia subReddit. 2017.)

“The first time that I heard a scent was back in high school chemistry lab. We were experimenting mixing chemicals with bromide compound which produces very strong odor. I "accidentally" smelled it at a close range and I heard a 'sharp' sound on my ears. It was like hearing it with earphones. I was startled a little and thinking the whole day about what happened. Since then I realized I've been hearing smells my whole life. But I don't hear it all the time, only strong smells and not all scents. Perfumes trigger hearing the most (this is why I have so many perfume collection). (…)

For me, the most vivid sound was made by Zara Vibrant leather. It wasn't really an instrument, but an object making a sound. It's like a heavy string being plucked and distorted and then followed by some other bowed string but lighter and higher. Another fragrance, a cologne by local brand Casablanca Homme Ambitious makes a low hum and high crystal-metallic sound.

Music mostly comes on depending on the mood. The same fragrance can have different music too also depending on my mood and vibe. For me, Zara vibrant leather can have 2 music following it, sometimes low rhythmic beats like techno and the other times it's string instrumental like violin. The music only lasts like one or two secs. (…) Yes I think it has something to do with the top, middle, and base notes.”

(Source: An interesting conversation following a post on the Synesthesia subReddit. 2020.)

Olfactory-auditory synesthesia in the Ming Dynasty?

A fourteenth-century Chinese poet wrote about hearing the smell of flowers

Artist Ninghui Xiong and author Pat Duffy have contributed an article to ResearchGate (you can read it here) about the poem “The Pavilion for Listening to Fragrance” by the ancient poet Zhang Yu (1333-1385). They made an online presentation about it at the Synesthesia Conference in Spain in October 2022. The photo below shows Ninghui and Pat at the 2018 conference with Ninghui’s painting inspired by the poem. Here is the English translation:

“Brilliant, bright –the flowers of the season!
Their subtle fragrance arises in the quiet. Others are hoping to smell them a few times, but I prefer to use my ears!
Their fragrance sends forth jewel-like songs; singing them out loud I feel such joy!
And who says there is no fragrance in sound?
Smelling and hearing are really the same thing”.

(Chang Yu (1333-1385) “The Pavilion for Listening to Fragrance”, quoted in The Columbia Book of Later Chinese Poetry: Yu’an, Ming, and Ch’ing Dynasties 1279-1911, translated and edited by Jonathan Chaves. New York: Columbia University Press, 1986.)

Cross-modal correspondences

Consciously and involuntarily hearing sounds in response to different smells is a rare phenomenon that occurs in synesthetes, but most people can make a connection between smells and auditory tones if they are asked to do so. This study (O. Deroy, A-S. Crisinel, C. Spence, 2013) explores the subject in depth and mentions the case of perfumers, who make good use of musical vocabulary on creating their aromas:

“Perfumers often talk about the composition of a fragrance in terms that look strikingly similar to those used by musical composers: that is, they search for the right balance and harmony between high and low notes, they think about tones, and so forth.”

The Cheese Symphony

A superb example of smells suggesting different notes, timbres, melodies and musical sounds – literary, in this case, and quite well-known – can be found in the novel Le Ventre de Paris (The Belly of Paris), written in 1873 by Émile Zola, the leading figure of naturalism and one of the most important writers in the history of French literature.

Zola takes his readers to a cheese stall in the central Parisian market of Les Halles, where

“…Every now and then, however, a slight whiff, a flute-like note, came from the parmesan, while the bries came into play with their soft, musty smell, the gentle sound, so to speak, of a damp tambourine. The livarot launched into an overwhelming reprise, and the géromé kept up the symphony with a sustained high note. From the cantal, Cheshire, and goat’s milk came the sound of a bassoon, punctuated by the sudden, sharp notes of the neufchâtels, the troyes, and the mont-d’ors.”

The author is not known to have had olfactory-auditory synesthesia (or any other type). He simply drew an enthralling parallel between a mixture of strong smells and music, describing a cross-modal correspondence that all his readers could understand.

(Source: the novel Le Ventre de Paris, in its English translation in Oxford World’s Classics, available online at pdfdrive).

More information on Zola’s cross-modal perception and sensory writing here: Modern Sensitivity: Émile Zola’s Synaesthetic Cheeses.

Types of synesthesia related to olfactory-auditory:

Taste-sound (gustatory-auditory)

Colour-sound

Pain-sound

Olfactory-visual (smell-colour and smell-shape)

Olfactory-tactile

This page last updated: 19 February 2023