You cannot use it on Yom Tov, but a new smartphone app may be about to revolutionise Rosh Hashanah.

Wake Up World allows children — and their young-at-heart relatives — to use a phone or tablet as a shofar.

By blowing into a microphone youngsters can hear the traditional blast of the horn sounded back through the device’s speakers.

The app was created by G-dcast, a San Francisco-based Jewish media production company. It features a main character using the shofar to wake up friends to navigate their way through a story.

G-dcast hopes families will use the app — which is available in Hebrew and English and is free to download — as an alternative High Holy Days bedtime tale.

Wake Up World is narrated by social media guru Randi Zuckerberg, sister of Facebook founder Mark Zuckerberg. She said: “This story is a whole new way to engage children around Jewish education. Growing up, stories like this were so important to me. It’s great to see my son getting the same kind of message, in a different way.”