Why Mobile Phones are Annoying

by Jakob Nielsen on April 12, 2004

Summary: Bystanders rated mobile-phone conversations as dramatically more noticeable, intrusive, and annoying than conversations conducted face-to-face. While volume was an issue, hearing only half a discussion also seemed to up the irritation factor.

Andrew Monk and colleagues from the University of York have performed a wonderful study to assess why it's so annoying when other people have cellphone conversations in public.

The researchers staged one-minute conversations in front of unsuspecting commuters who were either riding a train or waiting for a bus. In half the cases, two actors conversed face-to-face while seated next to a potential test participant. In the other half, a single actor talked on a mobile phone while seated next to a potential participant.

Furthermore, the actors conducted half of the conversations at a normal loudness level , whereas the other half were exaggeratedly loud (as measured on a volume meter). The actual content and duration of the conversations were the same in all conditions.

After each test conversation, researchers approached the bystanders and asked them to complete a small survey about the conversation. In other words, while the conversation was taking place, the participants didn't know that they were part of an experiment , but rather assumed that the conversation was the normal behavior of one or two other commuters.

The Consent Question

Some people might question the ethics of conducting research without first acquiring participants' informed consent, but in my view, this was a perfectly ethical study. The real question is whether you're harming participants, not whether you're pushing enough paper around to satisfy a bureaucracy.

In this case, it would have been impossible to have people first sign a statement that they would observe a conversation and then comment on it. Knowing about the conversation in advance would completely change the participants' experience. Also, in this study, if a person didn't want to participate, all they had to do was refuse to answer the questions. Overhearing a short conversation in public is a common phenomenon; it does no harm and falls within the ethical guidelines for usability studies.

(The ethics of usability is one of the topics covered in my 3-day camp teaching Usability in Practice at the Usability Week 2009 conference in Washington DC, San Francisco, London, and Sydney. )

Study Results

The results were as follows. The numbers indicate the average rating on a 1 to 5 scale, with 1 being most favorable.

The first table compares bystander ratings for mobile-phone conversations versus face-to-face conversations:


  Conversation was very noticeable Conversation was intrusive Volume of conversation was annoying Average
Mobile phone 3.4 2.5 2.4 2.8
Face-to-face 1.8 1.4 1.6 1.6


The second table compares bystander ratings for conversations at different levels of loudness:


  Noticeable Intrusive Annoying Average
Loud voice 3.2 2.4 2.4 2.7
Normal voice 2.1 1.5 1.6 1.7


Clearly, mobile phones score far worse than face-to-face conversations, confirming much anecdotal evidence. As we might expect, loud conversations score worse than quieter conversations. It's striking, however, that mobile-phone conversations are judged more negatively than loud conversations. Participants even said that the volume of the mobile-phone conversations was more annoying than those that occurred face-to-face, even though the volume was the same, and was controlled by objective measures.

Can We Make Mobile Phones Less Annoying?

The researchers asked test participants to rate how annoyed they were by the mobile phone's ring tone . (No comparable question applied to the face-to-face condition.) However, people didn't find the ring to be particularly bad, so the fact that mobile phones ring doesn't seem to explain why bystanders hate mobile-phone conversations.

Speech volume did affect bystanders' annoyance level: loud phone conversations were judged more negatively than phone conversations conducted in a normal voice. Designing phones that encourage users to speak softly will reduce their impact on other people. For example, more sensitive microphones and improved quality on incoming audio will make most users less inclined to shout.

But loudness wasn't the worst problem with mobile phones. In fact, even phone conversations in a normal voice received worse scores than face-to-face conversations. The worst problem seems to be that conversations on mobile phones are more noticeable than face-to-face conversations. This seems odd, since two people talking together project twice the amount of audio as one person talking on the phone.

Unfortunately, Monk and his colleagues don't provide the final answer; more research is called for. But the problem seems to be that people pay more attention when they hear only half a conversation . It's apparently easier to tune out the continuous drone of a complete conversation, in which two people take turns speaking, than it is to ignore a person speaking and falling silent in turns.

Based on this early research, it's hard to know how we might design phones that overcome the turn-taking problem in audio projection. Speakerphones might be an answer, but I don't think so.

What is certain is that the research documents the fact that mobile phones are annoying, and that conversation loudness is only one factor. If mobile-phone vendors want to avoid a backlash against their products, they're well advised to heed these findings and launch a major effort to make mobile phones less irritating to bystanders.

Methodology Advances

Even though these findings raise more questions than they answer, I find this study interesting for two reasons.

  • It pioneers the study of bystander usability . It's not enough to test usability with a design's direct user. We must also consider those who are getting a "user experience" whether they want it or not. This question will become more important as user interfaces leave the screen behind and become physical and/or mobile.
  • It's a great example of field research and of collecting participant data in a naturalistic context. Staging scenarios with actors is an unusual method in usability research, but such methods might become more common as we move into testing collaborative systems and environmental designs.


Andrew Monk, Jenni Carroll, Sarah Parker, and Mark Blythe: "Why are Mobile Phones Annoying?" Behaviour and Information Technology , vol. 23, no. 1, 2004, pp. 33-41.


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