There’s nothing that gets the rumour mill working overtime quite like an upcoming iPhone announcement. Projection keyboards, glass cases and flexible screens have all been mentioned as potential developments in the iPhone over the years.

While we may be a few months off yet, the speculation is already increasing as claimed leaks point to possible features in the iPhone 7. Apple has always tried to keep details of its new phones under wraps but it's a feat that is becoming increasingly difficult.

First, as few things we can be reasonably sure of. Despite the introduction of the iPhone SE, which moves back to the iPhone 5s style and size, the iPhone 7 is set to carry on the standard set by the iPhone 6 and 6 Plus: two sizes, one with a 4.7-inch screen, the other 5.5 inches. The design won’t change too much either, if the leaks are accurate.

There will be an upgrade in the chip, with the current A9 processor superseded by the new generation. And we should see it all around the middle of September.

But what else can we expect from the updated iPhone? Here’s a few of the rumours doing the rounds.

1. Four speakers:

The iPad Pro, when it launched, came with four speakers, and the difference in sound is notable. Could the iPhone 7 mimic its larger sibling? A leaked photograph of what is claimed to be a case for the new iPhone seems to suggest so. Published on French blog Nowhereelse.fr, the photograph shows space for four speakers in protective case, indicating that Apple may be going for the quad set-up.

2. Headphone jack? What headphone jack?

The move to a lightning based headphones has been rumoured for some time. But the previously mentioned photograph of the case seems to give more weight to the speculation that the iPhone 7 will ditch the 3.5mm jack. It’s not all good news though, the obvious problem being that the expensive headphones you’ve invested in won’t fit into the iPhone without an adapter of some sort.

3. Dual cameras

The Huawei P9 already uses dual cameras and the online rumour-mill claims the iPhone 7 will be going down the same line - at least for the 5.5 inch version. That means better, more detailed photographs from your camera phone, as well as opening up the way for more advanced features such as 3D mapping.

4. Optical image stabilisation for all

Optical Image Stabilisation has been the saviour of many a shaky shot. The technology, which is designed to take the worst of the judders out of your footage, has been included in the iPhone 6 Plus and the 6S Plus, but the 4.7 inch version of the iPhone has so far had to do without. If rumours are true though that is about to change, with expectations that the technology will be included in both versions of the iPhone 7.

5. New colours

There was a stage where the only colour an iPhone came in was black. Then Apple added white to the lineup and things started to develop. Rose gold, space grey, silver and gold could be joined by a purple version, although we’re less sure that we like this development.