gistfile1.txt

> db.test7.insert({firstName: 'testme',lastName: 'testme', devices: [{address: 'testme@not.a.domain', type: 'EMAIL'}]})
> db.test7.ensureIndex({'devices.address': 1, 'devices.type': 1})
> db.test7.find({devices: { $elemMatch: {address: /^testme/, type: 'EMAIL'}}}).explain()
{
        "cursor" : "BtreeCursor devices.address_1_devices.type_1 multi",
        "nscanned" : 1,
        "nscannedObjects" : 1,
        "n" : 1,
        "millis" : 1,
        "indexBounds" : {
                "devices.address" : [
                        [
                                "testme",
                                "testmf"
                        ],
                        [
                                /^testme/,
                                /^testme/
                        ]
                ],
                "devices.type" : [
                        [
                                "EMAIL",
                                "EMAIL"
                        ]
                ]
        }
}
> db.test7.find({devices: { $elemMatch: {address: {$regex:"^testme"}, type: 'EMAIL'}}}).explain()
{
        "cursor" : "BasicCursor",
        "nscanned" : 1,
        "nscannedObjects" : 1,
        "n" : 1,
        "millis" : 0,
        "indexBounds" : {

        }