For commuters, a journey on public transport can now come with an unexpected soundtrack: someone else's smartphone. A passenger watching videos without headphones, streaming music through a phone speaker or taking a call on loudspeaker turns what should be a private activity into something everyone nearby can hear. The habit has acquired names including “loudcasting” and “sodcasting”, and growing public frustration is prompting transport authorities, politicians and businesses to reconsider how phone use should fit into shared spaces. Ofcom's 2022 research found that 46% of people had watched videos without headphones in public, while 45% had made video calls and 36% had listened to music without them. The behaviour was particularly common among teenagers. Among 13-to-17-year-olds, 83% considered watching videos without headphones acceptable, compared with 21% of people aged 55 and above. At the same time, eight in 10 people said loudcasting annoyed them. Newer polling suggests the irritation has persisted. A 2025 YouGov survey found that 79% of Britons were bothered by people playing music or videos through phone speakers, including 41% who said they were bothered "a great deal". The divide is therefore not simply about whether people use their phones loudly. It is also about what different generations consider acceptable behaviour in public. Why do people loudcast? Researchers studying technology and behaviour argue that loudcasting can serve purposes beyond simple disregard for others. For younger people, smartphones are often social devices. Friends travelling together may watch content, listen to music or make video calls collectively. Playing something aloud can also become a form of self-expression, allowing users to display their musical or entertainment preferences to people around them. This helps explain why the behaviour can appear perfectly ordinary to one passenger and deeply irritating to another. The phenomenon itself is not entirely new. Previous technologies, from portable radios to boomboxes, generated similar arguments about noise in shared environments. Even early mobile-phone users could attract disapproving looks for speaking on their devices in public. What has changed is the scale of what a smartphone can deliver. A single device can now stream video, music, social-media content and live conversations almost anywhere. Faster mobile networks and increasingly accessible data have made consuming that content while travelling easier, reducing the practical barriers that once encouraged people to wait until they reached a private space. Why does phone audio feel so intrusive? The irritation may also have less to do with volume than with context. Researchers who study soundscapes distinguish between noises people expect to hear in particular environments and sounds that appear out of place. Passengers generally expect the noise of engines, brakes and railway tracks on public transport, allowing them to become accustomed to those sounds. A stranger's conversation or video is different. It contains information that the brain may automatically try to process, while unpredictable changes between speech, music and video clips repeatedly attract attention. The result is that a relatively quiet smartphone can sometimes feel more disruptive than a louder but predictable background noise. The Covid-19 lockdowns may have complicated those social expectations further. People spent prolonged periods consuming media and communicating from home, where they did not have to negotiate the same public-space etiquette. Some researchers argue that certain habits may have followed people back into shared environments. Should loudcasting be punished? The debate has increasingly moved from social etiquette into policy. Transport for London has repeatedly encouraged passengers to use headphones, while its earlier research found loud mobile conversations and audible headphone music were already among the most commonly witnessed forms of inconsiderate behaviour. The Liberal Democrats have called for tougher penalties, including fines of up to £1,000, while a 2025 YouGov poll found that 62% of Britons supported fines for playing music or videos aloud on public transport. However, Britain already has legal mechanisms for dealing with disruptive noise. Railway byelaws prohibit behaviour that interferes with other passengers' comfort or convenience and restrict sound-producing equipment when it causes annoyance. Updated railway byelaws came into force in 2025. The Bus Services Act 2025 has also expanded the powers available to local transport authorities to create and enforce passenger-behaviour byelaws. Businesses are beginning to establish their own rules as well. In August 2026, Wetherspoons introduced a policy across its 792 UK pubs prohibiting customers from playing music or taking calls through phone loudspeakers, following complaints about disruptive noise. A global problem with different social rules The dispute is not uniquely British. Countries differ considerably in how strongly public spaces are governed by expectations of quiet. Japan, for example, has strict social norms around phone use on public transport, while other more individualistic societies may tolerate louder personal behaviour. Ofcom's research also found differences in loudcasting behaviour between ethnic groups, but negative reactions remained high across all groups, suggesting that the behaviour cannot be explained simply through ethnicity. Age, social context, cultural expectations and individual technology habits are likely to intersect. The central question is therefore not whether smartphones will continue producing sound in public. They almost certainly will. The question is whether society will continue treating that sound as a breach of etiquette, introduce stronger rules to control it, or gradually become so accustomed to it that another person's phone becomes just another part of the public soundscape.