Spoken by over 9 million predominantly Scandinavian-based people, Swedish is one of the more minor European languages. Like Danish and Norwegian, it derives from the North Germanic language known as Old Norse. But what are the specific features that make it sound so unusual?
The reason Swedish sounds so unusual is because of its unusual prosody. The way syllables are stressed in Swedish gives the language a sing-song tonal quality.
Swedish also has a number of vowel sounds and vocal effects that are either relatively rare or unique to the language.
The remainder of this article will provide insight into what makes Swedish so unique by exploring some peculiar features of the language that set it apart from other languages.
Also see Why Do Swedes Have Blonde Hair? to learn more.
What Does a Swedish Accent Sound Like?
A Swedish accent sounds melodic and is punctuated by unusual vocal effects. Rules governing the way syllables are stressed give Swedish its unique sing-song quality.
The language is also characterized by a large number of vowel sounds and closed syllables with consonant clusters.
The immediately noticeable quality of Swedish that most clearly sets it apart from most other languages is its unique prosody, which governs the way syllables are stressed in the language.
Swedish is the only pitch-accented European language other than Norwegian.
Swedish prosody differentiates two kinds of accents according to which words are enunciated.
These are referred to as the acute accent–which is characterized by a falling emphasis–and the grave accent–which is characterized by a falling-rising-falling emphasis.
In the acute accent, a falling emphasis in the stressed syllable is followed by a further fall in the unstressed syllable.
On the contrary, in the grave accent, the initial fall in emphasis on the stressed syllable is followed by a rise in emphasis on the unstressed syllable, followed by a final fall.
This unique prosody means that many Swedish words that are spelled the same way will sound different and mean different things, depending on the context they are used in.
Thus, when listening to Swedish, one must pay attention to the pitch of the voice to understand what is being said.
The classic textbook example used to illustrate this is the Swedish word anden, which can refer to either a duck or a spirit depending on how the emphasis on the two syllables is read. 
Just among two-syllable words, there are over 300 examples of such words.
The unique modulations of Swedish also give it a characteristic rhythm that has a melodic quality. Thus, it is this unique prosody that makes it sound as if someone speaking Swedish is singing.
Swedish also has an unusually large number of vowel sounds. Along with the five English language vowels – a, e, i, o, and u – Swedish also considers y a vowel and has three unique vowels: å, ä, and ö.
Each of the nine vowels can be pronounced in two different ways based on length, making for 18 unique vowel sounds.
Like other Germanic languages, Swedish boasts a large number of closed syllables, with short vowels closed by clusters of up to eight consonants.
It also has many digraphs (pairs of consonants that make up one sound) and trigraphs (trios of consonants that make up a sound).
Apart from its large number of vowel sounds and long strings of grouped consonants, Swedish is known for other unique vocal effects that are not found in other languages.
These include the voiceless dorso-palatal velar fricative (the sje-sound) and the Viby-i. 
Its melodic speech patterns, large number of vowel sounds, long strings of grouped consonants, and other unusual vocal effects give Swedish a unique character.
While it does bear some resemblance to languages like Norwegian and Danish that derive from a common language, Swedish sounds distinct from any other language.
Also see Why Does Sweden Have So Many Islands? to learn more.
Why Does Swedish Sound Like Singing?
Swedish sounds like singing because of its unique prosody. There are two accents by which words are enunciated depending on their context.
Thus the same word can be characterized by a falling emphasis and a falling-rising-falling emphasis.
Swedish is a rare pitch-accented language, the only one in Europe other than Norwegian.
This means that the pitch of the accent, i.e., the emphasis on the individual syllables in a word, has a bearing on the meaning of what is spoken.
Swedish has two accents:
- An acute accent
- A grave accent
In the first, a two-syllable word consisting of a stressed syllable followed by an unstressed syllable is pronounced by a continuous dip in emphasis.
This can also be referred to as a falling emphasis.
In the second (grave) accent, the initial fall in emphasis on the stressed syllable is followed by a rise and a fall on the unstressed syllable.
That is why the grave accent is referred to as having a falling-rising-falling emphasis.
The modulations in spoken Swedish, as a result of its unique pitch-accented prosody, cause it to have rhythmic fluctuations that are melodic.
These rhythms can give the impression that a person speaking Swedish is singing.
Also see Why Does Sweden Have So Many Metal Bands? to learn more.
What Is the Strange I-Sound That Swedes Make?
The strange i-sound that Swedes make is known as a Viby-i or Lidingö-i. It is described as a long i, with a “thick” or “buzzing” quality.
Said to originate in the affluent Stockholm suburb of Lidingö, it is read as a marker of the speaker’s prestige.
As mentioned above, Swedish has one of the largest numbers of vowel sounds of any language. It pronounces each of its nine vowels–a, e, i, o, u, y, å, ä, and ö–two ways. Each vowel also has a short version and a long version, making for a total of 18 vowel sounds.
The Viby-i or Lidingö-i is a dialect-specific pronunciation of the long-i that is produced using a unique articulatory strategy.
Commonly, it is produced by using a low, fronted tongue body and raised tongue tip, accompanied by post-dorsal retraction.
As the dialect is said to have originated in the affluent Stockholm suburb of Lidingö, it is seen as a marker of the relatively high status of the speaker.
Today it is widespread in Central Sweden, where it has largely displaced the Standard Swedish pronunciation.
A significant factor in its spread has been the dominance of mass media by Swedish elites.
Swedish sounds unusual because of its relatively rare pitch accentuation, unusually large number of vowel sounds, lengthy consonant clusters, and other unique vocal effects.
Also see Do Swedes and Finns Get Along? to learn more.