Can people tell whether someone smokes or does not smoke by only hearing the sound of their voices? Can they tell the difference between a male and female voice? That is a question I attempted to answer by doing this science fair project. My hypothesis is that you can tell if someone smokes because the frequency of their voice is lower than normal. The purpose of this project was to assess whether the voice differences between smokers and non-smokers can be accurately distinguished by 3 groups of evaluators consisting of adult voice experts, adult non-experts and minors. The evaluators were asked to listen to the voices of 40 subjects, 20 of whom were smokers and 20 of whom were non-smokers. All subjects were recruited from the Montreal General Hospital. The evaluators had no knowledge of the participants and based their evaluations on the digital audio recordings only. This is because physical appearance may give clues as to whether someone smokes or not. The evaluators then recorded their findings on a data sheet. The dependent variable in this study was the evaluators that completed the questionnaire and the independent variable was the group of patients heard in the audio tape.
Cigarettes have a huge impact on society because one third of the world’s population smokes. Smoking claims 10,000 lives every day and 3.5 million per year which is roughly the population of the entire island of Montreal (1). Cigarettes are made from the tobacco plant which is harvested to make cigarettes. Typical cigarettes consist of 90% tobacco. The reason why many people smoke cigarettes is because they contain nicotine, a very addictive substance (2). There comes a point where people get so hooked on nicotine that they cannot stop smoking. Smoking is a terrible habit to start because of its long list of devastating health consequences such as lung cancer and strokes.
Tobacco and smoking have a long history. Scientists estimate that tobacco first started growing in the Americas around 6000 B.C. People only started using it to smoke or chew around 1000 B.C. (3). Most researchers think that the first users of this harmful product were the Mayans, in Central America. When Christopher Columbus discovered the Americas in 1492 he was given gifts from an aboriginal tribe, which included fruit, wooden spears and tobacco (3). Christopher Columbus became the first person that did not live in the Americas to touch, see and smell tobacco leaves. However, Columbus never actually smoked the leaves because he threw them away. Later that year, a Spaniard by the name of Rodrigo de Jerez, while searching for China, landed on the island of Cuba. He was the first non-native to actually smoke tobacco. When Jerez returned to Spain, the people claimed that he had “smoke coming out of his mouth and nose” (3). He was given seven years in prison because he was thought to be part of the devil. When seven years passed, smoking had become popular in Spain. The Europeans started growing tobacco in colonies that they had conquered in the Caribbean. They saw tobacco as a substance that cured many ailments and smoking became more and more popular across the world. Romantic films from the 1930s to the 1970s often had men and women that smoked. Back then, people believed that it gave them a “sexier voice” because it made their voice lower. In the early twentieth century, some doctors recommended cigarettes to patients to help them cough up harmful things that they had in their lungs.
You may be wondering how smoking affects the voice. The answer is that in your throat you have an organ called the larynx, more commonly known as the “voice box”. The larynx contains the vocal cords which vibrate and allow you to speak. These are normally fairly thin. The vocal cords separate, or open, for breathing (Figure 1). They come together for sound production (Figure 2). The lungs and tongue also play an important role in speech. The lungs provide the air that passes through the ‘closed’ vocal cords and makes them vibrate, resulting in sound production. This sound is modulated into speech by the throat, tongue, lips and teeth(4,5). The tissues covering the vocal cords are very sensitive to toxic substances. When someone smokes, the vocal cords get swollen and become thicker making the voice’s pitch or frequency drop. When someone smokes a cigarette, their voice deepens, and then becomes normal again (6). If the person is a chain smoker then the vocal cords don’t have time to recover and the frequency may drop permanently.
Figure 1: View of voice box (larynx) during breathing. The vocal cords are open.
Figure 2: View of voice box (larynx) while sound is being made. The vocal cords are closed.
Figure 3: Voice box (larynx) of smoker
The normal fundamental frequency (pitch) in men is around 110 Hz while in women it is around 200 Hz. A study done in 1987 by C. H. Murphy and P. C. Doyle (6) showed that an individual’s vocal frequency can decrease very quickly after they have smoked a cigarette. One test subject’s voice was recorded initially at 210 Hz. Twenty-five minutes after the person smoked a cigarette her voice was recorded at 197 Hz. Another test subject’s voice was recorded at 226 Hz and 25 minutes later, the same person’s voice was recorded at 218 Hz. The authors also showed that the fundamental frequency recovers or returns to normal after 40 hours of non-smoking. However, after a certain point, the damage done by the harmful chemical becomes permanent. In 1982, David Sorensen and Yoshiyuki Horii (7) conducted a study that proved that there is a significant difference in the fundamental frequency of smokers and non-smokers’ voices.
I chose this topic because I am interested in the many adverse effects of smoking on humans. Smoking is linked to lung cancer, vocal cord cancer, high blood pressure, heart attacks, asthma, emphysema and other diseases. Another controversy in this field of research is secondhand smoke because it jeopardizes the health of non-smokers(8). A study conducted by Paul Brennan and others showed that individuals that were exposed to secondhand smoke were 13% to 32% more likely to develop lung cancer. Knowing that smoking affected vocal frequency, I thought it might be possible to distinguish between a smoker and non-smoker based on voice alone. I also wanted to know if voice experts, such as specialized voice doctors and speech therapists could do a better job at telling the difference than non-experts or minors.
The goal of my science fair project is to see whether the voices of smokers and non-smokers can be distinguished by 3 groups of evaluators: three adult voice experts, two adult non-experts and two minors. This topic has some definite applications. If you asked people to name one effect of smoking, chances are they would probably say lung cancer. The effects on voice are either overlooked or probably unknown to the public. However, just because it is overlooked doesn’t mean that it is not harmful to the individual that is smoking. If young people knew how obvious their voice changes were they might not want to smoke. The voice change caused by smoking could have some serious effects because it could ruin a singing career or other career opportunity. This project could hopefully lead to a decrease in youth smoking rates. It could also make adults realize what smoking can do to their body. Like many other people, I don’t want smoking present in our society because it is harmful to the people that smoke and the people who inhale secondhand smoke. If young people stop smoking they will have healthy voices and our society will be healthier as a whole.
Larynx: The organ in the throat that contains the vocal cords and is located in the upper part of the trachea.
Vocal Cords: Two ligaments covered by a thin lining that vibrate to produce sound that is located in the larynx. The two ligaments are like stiff elastic bands, and behave like the strings of a musical instrument.
Tobacco: A tall plant that is used in cigarettes.
Nicotine: A poisonous and addictive substance found in tobacco.
Secondhand smoke: Cigarette smoke that is inhaled accidentally by non-smokers.
Fundamental Frequency: The normal pitch of someone’s voice measured in Hertz.
Pitch: The frequency of a voice or how high or how low the tone of a voice is.