We’ve all been there. The end of term is finally in sight. Suitcases are packed, alarms are set, and in just a few hours it will be time to leave for the best trip imaginable – skiing in fresh mountain snow or heading somewhere sunny with a beach waiting at the other end. It’s the night before departure and sleep is almost impossible; excitement wins. Morning arrives early, fuelled by adrenaline rather than rest. Everything feels perfect – until that first swallow.
It hurts. A cold is coming.
By the end of the day, your ears feel blocked, your nose refuses to stop running, your lips are chapped and your voice drops an octave.
This is unfortunately, based on a true story.
But why do our voices suddenly become deeper, rougher or even completely different as soon as we get a cold?
Our voice is produced in the larynx – a structure in the neck often more commonly referred to as the ‘voice box’. Inside the larynx are the vocal chords (or vocal folds) which are two bands of tissue that vibrate as air passes through them when we speak.
The pitch of your voice depends mainly on the tension of the vocal chords, their length and their thickness. The thinner, tighter vocal chords vibrate faster, producing a higher pitch. Thicker or looser vocal chords vibrate more slowly, producing a lower pitch.
So where does a cold come into this?
A cold is usually caused by a viral infection affecting the upper respiratory tract. Your immune system responds with inflammation – redness, swelling, heat and increased mucus production.
When inflammation affects the larynx, it causes a condition called laryngitis (from the Latin larynx and the suffix -it is meaning inflammation). This inflammation causes the vocal chords to swell, become thicker and retain fluid.
When the vocal chords swell, their mass increases. In physics terms, increasing the mass of a vibrating object lowers its frequency and as most of us know, a lower frequency means lower pitch, which is why our voices sound deeper.
But then again, why does it also sound hoarse?
As well as a deeper voice, it also sounds rough or croaky which is because the swollen vocal chords cannot close properly so the vibrations become irregular and excess mucus interferes with the smooth movement. So instead of vibrating smoothly, the vocal chords produce a more distorted sound wave – which we perceive as hoarseness.
Colds also increase mucus production (which I am sure you would have experienced). While mucus is protective as it traps pathogens, it can coat the vocal chords and disrupt their normal vibration. This further alters the sound quality, making the voice sound muffled and unstable.
So, next time you sound like you’ve suddenly developed Justin Biebers singing voice in ‘that should be me’, you’ll know that it is just inflammation increasing the mass of your vocal chords and lowering their vibrational frequency.
Biology is always in action, even when you are constantly reaching for tissues.
I hope you learnt something new and I look forward to seeing you next week for a new question and a new answer in my series ‘questions that need answers’.
