Glottal Stops

Have you ever heard of a glottal stop? Probably not. But it's very likely that you have heard a glottal stop, since they are actually very frequent in English. You've probably never really noticed them, or just taken them for granted, but glottal stops are actually important sounds in the languages of the world, and often used creatively. Let's talk a little bit about glottal stops today.

If you've seen my IPA page, you'll know that a stop is what happens when you have a build-up of air that is suddenly released. The "glottal" part tells you that this is formed by the glottis, also known as the vocal cords. In a glottal stop, the vocal cords close, air builds up behind them, then the cords open quickly, resulting in a burst of air. It can be hard to hear the glottal stop, but think about the exclamation "uh-oh!" There's a sound between the "uh" and the "oh", isn't there? The two vowels don't flow seamlessly into each other. That sound in the middle is a glottal stop! The symbol for a glottal stop is ʔ.

But wait, there's more! In English, if you start a sentence with a word that starts with a vowel, there's a very good chance that that vowel will be preceded by a glottal stop. It's not uncommon at all for words with vowels at the beginning to have a glottal stop before them. If you speak American English, words like "button" and "mountain" have a glottal stop in them. "bu-n" [bʌʔn] and "moun-n [maʊʔn]." Some varieties of London English have Ts in the middle of words turn into glottal stops, so you have "bo-l" instead of "bottle." In most varieties of English, words ending in a vowel and then a stop have a glottal stop before the stop. This is known as "glottal reinforcement." To wrap up our list of examples, if you have a hiatus - when one word ends with a vowel and the next starts with the same vowel - a glottal stop can be used to break up that hiatus. So if you say "the eel" [ði il], that can be realized as [ði ʔil].

Some languages take glottal stops to the next level. They include glottal stops in their phonemic inventory. This means that glottal stops are considered sounds like "t" or "s" or "p" and words can be distinguished based on whether they have a glottal stop or not. This includes languages like Persian, Arabic, and Hawaiian.

Examples of Glottal Stops

Because glottal stops are not phonemic in English (it is not a sound in English the way it is in Arabic), most people are not aware of what they are or what they are called. Nevertheless, glottal stops are often used for effect.

In the movie "The Social Network," Mark Zuckerberg is fooling around during a business meeting. He's making some clicks (we'll talk about clicks in a different post). The client asks him what he's doing. Mark shrugs and says "some kind of glottal stop." Unfortunately, not a single one of those sounds was a glottal stop. It is still interesting to note that they chose to have him say "glottal stop" - did it sound cooler than "lateral click?" Did someone confuse a click with a glottal stop? Did the actor not understand how to make a glottal stop and just make clicks instead? This is a minor goof that has bothered me since I first watched this movie.

There are plenty of pop songs where a series of vowels separated by glottal stops constitutes the hook. You have Singles Ladies' "whoa-uh-oh, wuh-uh-uh, wuh-uh, oh, wuh-uh-oh" and Bad Romance's "ra, ra, a-a-a."

Sometimes glottal stops appear in unexpected places. In a live performance of "Wake Me Up When September Ends" from the live album "Bullet in a Bible," the lead singer of Green Day says "as my memor-y [mɛmɝʔi] rests." This is a pretty odd place to put a glottal stop, right in the middle of a word like that. He says it both times the line comes up as well. Oddly enough, he does not do this on the studio recording of the song.

Are Glottal Stops Harmful?

If you're a singer or an actor, you may have heard a vocal coach say that glottal stops are actually harmful for your voice. Here is an example of this attitude:

In drama school, however, I was told that glottal stopping was bad bad bad. My voice and speech teacher warned of the dangers of glottal stopping. “It can shred your voice,” he said. “It’s the worst thing you can do to your vocal cords.” In fact, he rarely referred to it as a glottal stop, but rather applied the scarier-sounding term, Glottal Attack. Yikes! And my voice and teach professor wasn’t alone among those in the voice and speech training community. Here is what renowned vocal coach Patsy Rodenburg has to say about the matter in her The Actor Speaks: "A compromise is necessary if the accent has qualities in it that can damage the voice … certain constrictions naturally present in some accents, could produce vocal abuse; glottal attack, for instance. You could speculate that native speakers of these accents have adapted sufficiently not to suffer this abuse." (Source)

A glottal onset bursts open the vocal folds, creating an almost grunt-like noise before the sound of the desired note. A glottal onset leads to a pressed sound (“pressed phonation”). Continued use of a hard glottal onset at high dynamic levels can potentially harm the vocal folds. (Source)

Is there any credence to the notion that high-pressure glottal stops can harm the vocal folds? First, notice that they are being specific. They are talking about glottal onsets (this is probably what "glottal attack" is referring to, since "attack" refers to the beginning of a sound wave). If you'll look back to our example about vowels, in English phrases starting with a vowel often begin with a glottal stop. This is what they are referring to. Glottal stops at the ends of words ("but"), or in a medial position ("button"), are unlikely to have enough pressure behind them to have a singing teacher worry that they would hard one's voice.

Ben T. Smith at Dialect Blog suggests that the reason vocal coaches discourage the glottal stop is due to classism. Working class South English accents, such as Estuary English, use glottal stops more frequently compared to standard varieties of English like Received Pronunciation. Smith suggests that distaste towards stigmatized accents is more to blame than any actual risk of vocal harm. He also notes that many languages all around the world use glottal stops regularly in multiple positions and have rich singing traditions. Arabic is a noteworthy one, as there is a long Arabic singing tradition and varieties of Arabic use the glottal stop. As far as I know, there is no epidemic of Arabic singers experiencing damaged vocal cords due to glottal onsets.

We shouldn't dismiss the notion entirely, though. Air coming in at high pressure puts strain on the vocal cords, and that is known to be harmful. It is not inconceivable that repeated use of very harsh glottal onsets at a high dynamic level (that is, loud volume) could contribute to vocal cord damage. Glottal onsets on their own, though, should not be any reason to worry.

Some vocal coaches worry about the quality of the glottal onset sound:

The ‘trick’ to executing an effective and healthy glottal stop is very much like that for staccato notes. Glottal adduction cannot be overly firm and the subglottal air pressure cannot be too high, or else the glottal stop will be ‘sluggish’ (instead of crisp and rapid) and the sound will be explosive and harsh. In other words, the throat must remain ‘open’ (rather than constricted and hyperfunctional) and the breath must be held back slightly with the inspiratory muscles (rather than forced out rapidly).

The singer first needs to develop consistent balance in the onset (‘attack’) of sound before attempting glottal stops. This can be accomplished through simple onset-release exercises performed on single notes, use of the ‘inhalare la voce’ [...] concept and the appoggio (the inspiratory hold whereby subglottal pressure is kept lower by resisting the premature ascent of the diaphragm). Work on staccato is often a logical next step. (The glottal stop requires a slightly longer and firmer glottal closure and closed quotient of the vocal folds than staccato, which in turn generates higher subglottal pressure, but both skills require control and balance between glottal adduction and the breath pressure.) (Source).

It is true that not all stops are created equal. Sometimes when we make a stop, we release more air compared to other times. Other times, less air is built up and it is released more weakly. The folks at "SingWise" are not suggesting that the issue is that glottal stops will ruin your voice, but rather that "poorly performed" glottal stops are stylistically undesirable for a singer.

Overall, the average person has no reason to worry about glottal stops ruining their voice. There are different reasons for avoiding them, like wanting to avoid stigmatized features of an accent or avoiding "sloppy" sounds when singing, and under unusual circumstances - like singing at high volume with poor technique and a lot of air pressure - it's possible that glottal stops could harm your vocal cords. If you are a singer or an actor, work with your vocal coach to use less high-intensity techniques to project your voice. Otherwise, carry on!

Note: I do not have access to medical journals (indeed, I have limited access to academic journals in general), so if you are aware of any scientific studies on the effects of glottal stops on the vocal cords in different situations, I would greatly appreciate any links in that direction.