Why do we say "Mmm" when we speak?

Have you ever had it happen that, while telling an anecdote, the word you are looking for does not come to you? Or that you start a sentence with all the confidence in the world and, halfway through, you need an 'mmm' to buy time? Maybe you are one of those who speak almost without stopping, but it could also be that you need to take a pause to organize your ideas before continuing. If you had to describe your way of speaking, what would you say? And do you think there is something in your rhythm that distinguishes you from the rest?

When we speak, we tend to be focused on the message: finding the right words, making ourselves understood, and not losing the thread of the conversation. Meanwhile, however, we also leave another type of trail: we prolong sounds, interrupt sentences, repeat words, and leave silences. These are details we do not pay much attention to, but they can be interesting when, instead of paying attention only to what a person says, we focus on how they say it.

Speech rhythm

A while ago, we talked about the clues that language can leave in a criminal investigation. This time, we will focus on a more specific aspect: the rhythm of speech. Could we distinguish two people by the way they pause while they speak? And, if we had to compare two recordings, would it be more useful to know at what speed someone speaks or to observe the pauses they make?

At first, when we think of a person who speaks quickly, we usually imagine someone who links words together without barely breathing. However, the speed we perceive does not always coincide with the one we can measure. In linguistics, in fact, a distinction is made between speaking rate and articulation rate.

The first calculates how many syllables we produce per unit of time, including pauses. The second measures the speed at which we articulate syllables without counting silences. The difference is important: one person may pronounce words very quickly and, yet, pause often; another may articulate more calmly, but speak in an almost continuous manner.

To understand this better, let's imagine two people explaining what they did over the weekend. One speaks calmly and hardly ever pauses, while the other pronounces words quickly, but makes pauses to recall details, organize ideas, or search for a precise expression. If we count the time each intervention lasts, the first might seem slower. If we discount the silences, however, the result might be different.

Furthermore, we do not speak the same way in all situations. When we read, the words are already in front of us; when we improvise a response, we have to find them while we speak, and, when we summarize a story, we have to select the information and explain it in our own words. For this reason, reading tends to be faster than spontaneous conversation and oral summary.

This difference leads us to ask the following question: if the same person can modify their rhythm depending on what they are doing, to what extent does speed allow us to distinguish them from someone else? Speed measurements, by themselves, do not always offer sufficiently clear differences between speakers. Perhaps, then, it is necessary to look at another aspect of rhythm that often goes unnoticed: pauses.

Think about the last time you explained something to someone. Perhaps the words came out all at once, but it is also possible that you paused before remembering a name or that you lengthened the end of a word while searching for how to continue. Surely, you did not even notice it, because these interruptions are common when we speak spontaneously and can appear for very diverse reasons.

They often appear simply because we need time to think about what we are going to say; on other occasions, a pause helps us to separate two ideas, emphasize information, or give way to the interlocutor. There are also the 'mmm's and 'eee's, which are called 'filled pauses' and which allow us to maintain the turn to speak while we search for the right words. Not all silences, therefore, are the same, nor do all hesitations have the same origin.

To study the rhythm of speech, therefore, it is not enough to count syllables or calculate how long an intervention lasts. We can also observe how many pauses we make and how long they last. With acoustic analysis programs like Praat, it is possible to identify silences and audible hesitations and study their characteristics.

If we do this, we will be able to verify that, when comparing different speakers, the frequency with which they stop can show differences that are not observed with the same clarity in speed measurements. The duration of the pauses, on the other hand, seems more conditioned by the communicative situation (in general, they are longer when we speak spontaneously than when we read).

This does not mean that each person has a fixed number of pauses that gives them away in any conversation, because, like most linguistic or speech traits, pauses are not a fingerprint of the voice. Thus, a conversation about a familiar topic can have a very different rhythm from that of an improvised intervention, and nerves, fatigue, and the complexity of what we want to explain can also modify the way we speak.

Frequency of pauses

However, the frequency of pauses could provide complementary information when we compare voices, provided that, at the same time, we assess the context in which the speech was produced and also take into account other characteristics of speech, never as definitive proof on its own.

When we speak, therefore, it is not only what we say that matters. It also matters how we distribute words in time: when we stop, how much time we need to continue, and how many times we interrupt the thread of the discourse. These are small details, often involuntary, that may go unnoticed in a conversation, but which are quite interesting when we set out to study how we speak.