Nightwish is one of the prime acts on the symphonic metal scene. The use of keyboards
through traditional piano and strings and the soprano
vocals of Tarja Turunen
, until her departure from the band in 2005, were distinct parts of their original sound.
The main musical influences on symphonic metal are early gothic metal, power metal and NWOBHM.
Music workstation keyboards and orchestras are often the focal point of the music, which, in essence, distinguishes the subgenre from other metal subgenres. Other instruments including guitars, bass and drums typically play relatively simple parts in contrast to the complex and nuanced keyboard and/or orchestral parts. Bands that do not use live orchestral instrumentation on their recordings or when playing live typically utilize factory presets on workstation keyboards (i. e., strings, choirs, pianos, pipe organs etc.) to conjure up a "pseudo-orchestral" sound, where parts are played idiomatically according to keyboard technique. This is particularly characteristic of less-known bands on tighter budgets. Some symphonic metal bands abstain from using keyboards entirely, choosing to use orchestral backing tracks, either recorded by a live symphony orchestra and/or choir during an album session, or recorded using virtual software instruments in a sequencer. This is particularly characteristic of bands that feature deeper and more complex arrangements that would be more difficult for one or even two keyboardists to reproduce in a live performance.
It is more difficult to generalise about the guitar and bass work found in this style. As with gothic metal, this can often be described as a synthesis of other rock and metal styles, with black metal, death metal, power metal, and progressive metal elements being the most common; but unlike in gothic metal, elements of classical music are frequently present as well. With varying frequency, the majority of bands in this subgenre employ these instruments (as well as the lead vocals) to play more simple, catchy melodies which arguably makes symphonic metal (along with power metal, which shares this characteristic) one of the more accessible metal subgenres.
Songs are often highly atmospheric, though more upbeat than those of other metal subgenres; even songs with morbid themes routinely feature prominent major-key fanfares. Particularly central to creating mood and atmosphere is the choice of keyboard sounds.
Lyrics cover a broad range of topics. As with two of symphonic metal's otherwise most dissimilar influences, power metal and opera (but also symphonic progressive rock), fantasy and mythological themes are common. Concept albums styled after operas or epic poems are not uncommon.
Bands in this genre often feature a female lead vocalist, most commonly a soprano. There is sometimes a second, male vocalist, as is also common in gothic metal. Growling, death-metal-style vocals are not unknown, but tend to be used less frequently than in other metal genres that make use of this vocal style (however, a notable example of its usage is by Mark Jansen in Epica). Further backup up to and including a full choir is sometimes employed.
It is very common for bands, almost exclusively female-fronted bands, to feature operatic lead vocals. Such bands can be referred to as operatic symphonic metal and include the likes of Epica, Nightwish (Tarja Turunen, then Floor Jansen), Haggard, Therion, Operatika, Dremora, Dol Ammad, Visions of Atlantis, Aesma Daeva, Almora and countless others. The operatic style is not exclusively tied to symphonic metal, and also appears in avant-garde metal, progressive metal, gothic metal and melodic metal.