Attempting synaesthesia

Trawling through Brian Kiteley’s writing prompts called “The 4am Breakthrough” I picked the following to write:
1. Synesthesia, according to M.H. Abrams in A Glossary of Literary Terms, is a description of “one kind of sensation in terms of another; color is attributed to sounds, odor to colors, sound to odors, and so on.” Here is an example of synesthesia from Bruno Schulz’s Street of the Crocodiles: “Adela would plunge the rooms into semidarkness by drawing down the linen blinds. All colors immediately fell an octave lower [my italics]; the room filled with shadows, as if it had sunk to the bottom of the sea and the light was reflected in mirrors of green water.” Schulz describes a change in color by means of a musical term. Writers consciously and unconsciously employ this peculiar method to convey the irreducible complexity of life onto the page. Diane Ackerman (in A Natural History of the Senses) feels we are born with this wonderful “intermingling” of senses: “A creamy blur of succulent blue sounds smells like week-old strawberries dropped into a tin sieve as mother approaches in a halo of color, chatter, and perfume like thick golden butterscotch. Newborns ride on intermingling waves of sight, sound, touch, taste, and, especially, smell.” Use synesthesia in a short scene—surreptitiously, without drawing too much attention to it—to convey to your reader an important understanding of some ineffable sensory experience. Use “sight, sound, touch, taste, and, especially, smell.” 600 words.

This is what I wrote:
It’s after lunch and the chair is not actually asleep, no not quite, but his brainwaves have levelled out. This is not the screaming flatline of a stopped heart, just the droning hum, the insistent fly on the window frustratedly burring, the cicada low-pitch keening, the heat of the afternoon murmuring punctured by occasional rising voices, footfalls, the sludge of the aircon whirring and spluttering. The depth of politeness and paralysis in the room does not allow us to rise above the surface of the sound of the speaker’s voice (which has no words, no meaning, no end) to call for help to the distant shore where the chair stares. Underneath the drone there is a rising sound from a distant place of sanity which says in increasing pitches: do not abuse my ears, do not presume on my patience, do not continue, stop, stop, stop. The speaker’s grey voice adds another line to the disharmony of the academic ritual of talk and listen. He is engrossed in his bland, unseasoned diatribe, his meal of wrongs done to him, his worthy experience of past repasts. This, however, is no snack, no tantalising bite. In fact, it’s a smorgasbord of breakfast cereals, thrown onto a table any old how, bran flakes, dry toast, rice crispies, rusks. There is no milk, no yoghurt, no jam, no butter. The speech sticks like a communion wafer. We retch and stretch our tongues, we reach for water, look for light, pale and aetiolated we pray, in some dim, dark, diminished, subterranean way, for release. Which comes, eventually, but instead of the green and blue-silver flash of a dam release this has a murky orange and red undertow, an anger rising, a boil bubbling, an injury of lava and ash, a flow of aggrieved yellow. How dare he presume to box my ears so? How dare he lean so far across the line of acceptable listening? How dare he ooze into my space with such brown presumption?