Can push notifications have sound?

What are push notifications?

Push notifications are messages that pop up on a mobile device, even when the user is not actively using the associated app. They allow apps to notify users of new messages, events, or other timely updates. Push notifications appear on screen similar to text messages.

According to Adobe, “A push notification is a message that pops up on a mobile device. App publishers can send them at any time; users don’t have to be in the app or using their devices to receive them.”

Push notifications allow apps to re-engage users and prompt them to open the app again. They enable timely alerts about things the user cares about.

Types of push notifications

There are several main types of push notifications that apps can send to users:

Alerts

Alert notifications display a message to the user when the app is not open. They provide information, warnings, or prompts to open the app. Alerts usually consist of a message and optional title. They may also include buttons that allow users to take quick actions straight from the notification.

Badges

Badge notifications update the app’s icon badge to show a visual count or indicator. The badge displays a number like the amount of new items available. It provides a simple visual cue without disrupting the user. Badges work well for apps like social media, email, or messaging.

Sounds

Sound notifications play audio when received. The sound catches the user’s attention even if the device is silent or has sound muted. Custom sounds allow apps to set their own audio clip or tone. Vibration can also accompany sounds on haptic devices.

Custom actions

Interactive notifications can include buttons for custom actions. Users can quickly trigger app functions like calling a number, opening a webpage, or composing a reply (CleverTap). Actions provide shortcuts that give users control straight from the notification.

Sound in push notifications

Push notifications can include custom sound on both iOS and Android devices. This allows apps to play a brief audio clip when a notification is received while the app is in the background. The sound helps notify and catch the user’s attention even if the device is muted.

On iOS, the audio file format supported is .caf. Android is more flexible, supporting common formats like .mp3, .wav, and .ogg (reference: https://stackoverflow.com/questions/63420587/fcm-custom-sound-not-working-on-ios-when-in-background-mode). The sound played can be a short melody, branded sound, or other audio customized for the app. Maximum length varies by platform.

Playing custom sounds with push notifications requires extra coding work to bundle the sound file and trigger it from the notification payload. Testing is also needed across device models to ensure broad compatibility (reference: https://github.com/vector-im/element-ios/issues/3666). When implemented correctly, it allows apps to stand out with audible alerts tailored to their brand.

Use cases for sound

Sound effects and custom sounds can enhance the user experience of push notifications in various ways. Here are some of the main use cases:

Notifications: A brief sound effect or chime can draw the user’s attention when a new notification arrives. This is especially helpful if the device’s screen is off or the user is focused on another task. Unique sounds can also help the user identify the app or type of notification without looking at their device.

Alarms: For time-sensitive notifications like calendar events, medication reminders, or tasks, a louder or more abrasive sound can convey urgency. This prompts the user to take immediate action when they hear the alarm sound.

Reminders: Softer, pleasant sounds can be effective for general reminders where timing is not as critical. For example, a digital windchime sound could remind the user to take a survey or drink some water periodically throughout the day.

Alerts: Important alerts about a developing situation like severe weather or traffic delays warrant sounds that are attention-grabbing yet not too harsh. The sound should be noticeable over other noises and signal to the user that they need to check the notification.

Overall, the optimal notification sound depends on the context and desired user response. Testing different sounds and getting user feedback can help identify the best options for each notification type.

Platform Differences

Push notification sound capabilities differ across platforms like iOS, Android, and Windows.

On iOS, custom sounds for push notifications must be bundled in the app itself according to the documentation from Braze. Supported audio formats include Linear PCM, MA4, and μLaw. iOS provides developers flexibility in customizing sounds.

For Android, push notifications can have default or custom sounds based on documentation from OneSignal. Custom sound files must be hosted at an internet-accessible URL. Android also allows adjusting sound stream properties like volume.

Windows supports custom sounds for its toast notifications according to Microsoft’s documentation. Sound files can be included in the app’s package or downloaded on demand. Only .wav files are supported for custom sounds on Windows.

So in summary, all major platforms allow custom sounds for push notifications in some capacity, but have slightly different requirements around sound file formats and delivery methods.

Customization

One of the key benefits of push notifications is the ability to customize the sound that plays when a notification is received. Platforms like iOS, Android, and web notifications allow developers to override the default notification sounds and use custom audio instead.

On iOS, custom sounds must be bundled into the app itself rather than hosted externally (see this Braze documentation). Developers can set a global default custom sound that will play for all notifications. Unique sounds can also be specified on a per-notification basis. This allows brands to use sounds that fit their identity and build consistent branding through audio.

For Android notifications, custom sounds can be specified either by file name or URI. Web push allows custom sounds hosted at a public HTTPS URL. In all cases, the ability to override default sounds with branded audio is an important tool for user engagement.

When implementing custom sounds, it’s important to consider accessibility and user preferences. Allowing users to opt out of custom sounds in favor of system defaults provides more control. Testing sounds across devices is also recommended, as audio playback quality may vary.

Best Practices for Push Notification Sound

When implementing sound in push notifications, following best practices ensures a positive user experience. Here are some key considerations around using sound effectively:

Use sound judiciously – only for high priority alerts where getting the user’s immediate attention is critical. Avoid overusing sound or it will become annoying. Allow users to control notification sound settings.

Allow customization – let users pick their preferred notification sound and volume level. This gives them control over the experience. Research shows that custom sounds have higher interaction rates than default sounds.

Mind the volume – pick sound effects that aren’t too abrasive at full volume. Softer chimes and rings work better than loud horns. Set a reasonable default volume, then let users adjust. Remember that notifications may play in quiet public settings.

Test on devices – notification sound rendering varies across platforms. Verify that your chosen sounds work as intended on different devices. Adjust audio compression if needed.

Check regulations – some locations have rules around notification sounds, like limiting volume. Verify compliance for the geographies you target.

Keep iterating – monitor metrics like interaction rates and opt-outs. Adjust your sound strategy based on what resonates with users.

Testing and optimization

A/B testing different notification sounds is important to find which tones and sounds resonate most with your audience and drive the highest engagement. Shorter and more subtle sounds may be better for frequent notifications, while longer or more musical sounds can make special offers stand out.

Analytics and engagement metrics should be closely monitored after launching or changing notification sounds. The number of users who open or interact with notifications based on different sounds can inform optimization.

Consider time of day testing as well – certain notification sounds and volumes may perform better during business hours versus evenings. Location-based tailoring can also be tested, using different sounds depending on a user’s locale.

Gradual iterative testing is advised, making small changes to sound selection, length, volume, and frequency over time. Be careful not to make sounds too disruptive or annoying. Offer user customization and settings to disable sounds if negative feedback is received.

Refer to platform guidance and regulations regarding notification sounds and volume. Monitor app store reviews and user feedback channels to catch any complaints early. Optimize notification sounds to drive engagement while maintaining user satisfaction.

Regulations and Compliance

Mobile platforms have regulations and guidelines around permissions, privacy, and accessibility for push notifications and sounds:

On iOS, you must get the user’s permission before sending push notifications or playing sounds. Users can revoke permissions at any time in Settings. To respect privacy, sounds should be subtle and not startle users.

The Android developer policies require consent before sending notifications and state that sounds should not be disruptive or annoying. Users can turn off notifications for an app in Settings. Apps must also provide accessibility options.

For web push notifications, browsers require user opt-in and permit notification sounds. However, sounds must not be excessive or invasive. Browsers allow users to customize notifications.

Apps should aim for judicious use of sounds, provide controls, and follow platform guidelines. Overall, respecting user permissions and preferences is key for compliance.

Future of Sound

The future of push notification sounds is exciting as new use cases and technologies emerge. Spatial audio is being explored by companies like Apple to create more immersive notification sounds. Spatial audio uses directional audio filters to make it seem like the sound is coming from a specific location rather than just generally from the device. This could allow push notification sounds to feel more natural and less disruptive.

New use cases for push notification sounds are also being developed. For example, some apps are exploring using custom voices for their push alert sounds. A ridesharing app could use a custom voice recording to notify you that your driver has arrived. Other apps may explore using spatial audio for navigation alerts that seem to come from the direction you need to walk or turn. As push notifications become more conversational, custom voices and spatial audio may create more engaging experiences.

Overall, the future of push notification sounds is moving beyond simple dings and chimes. More immersive spatial audio, custom voices, and innovative use cases will emerge. But apps will need to carefully consider the user experience to balance utility and delight.